Other than being good books, these recommendations are based largely on what I'm looking for in a beach read. Although Kindles have made it possible to read even the biggest George RR Martin tome wherever you want, I still think a beach read should ideally be relatively short, so that if you prefer to expose the paperback to sand, sea, salt, and (depending on the beach) rain it's not too huge, and you can reasonably expect to read the whole book during one short holiday.
I also quite like to read something appropriate to the environment when on a beach, so tend to avoid stories set in snow-bound mountains or similar, though again, this depends to an extent on the beach. (Classics-themed novels have an advantage there, of course, as Greece and Rome are quite warm - if you're European, chances are the beach you are on was once part of the Roman Empire).
And they should be reasonably light in tone for the most part, as convulsive crying because your favourite character has been tortured/sacrificed/behaved like a an idiot while reading on a public beach can be a little embarrassing. I've also restricted this list to novels, though I've often enjoyed reading non-fiction (especially travel literature) on a beach as well. There are a lot of mystery novels here, mostly because I like the genre, but also because the stories tend to be self-contained puzzles leading up to the satisfying conclusion of finding out whodunnit, so they work especially well as beach reads. (If you're wondering where my one of favourite Classics-based novels of all, I, Claudius, is, it was discounted for not being quite light enough in terms of readability - all those ancient-historian-inspired digressions - or weight, especially if you wanted both the novel and its sequel, Claudius the God).
I've been pretty broad in what counts as 'Classics-themed' here, so some of these are stories set entirely within the ancient world, while others just use Classical themes or include hints and elements of Classical mythology or culture.
10. The Evil That Men Do, by Nancy Holder
Between TVs in hotels, films on memory sticks, laptops, portable DVD players and so on, two-week holidays with no TV are much rarer than they used to be. But if you want something to read without requiring headphones on the beach, but find you're missing your TV, what better to bring than a TV tie-in novel?! I'm rather fond of official tie-in novels. Essentially fan fiction that's gone through a professional spell check, they're usually light, frothy and often good fun. This particular Buffy the Vampire Slayer tie-in novel comes with ancient Roman vampires, Bacchae and an amphitheatre - close your eyes to historical inaccuracy and enjoy.
9. Dead in the Family, by Charlaine Harris
I recommended Charlaine Harris' Southern Vampire Mysteries among my suggestions for geeky beach reads, and the same reasons still stand here - nice, hot setting, good pace, a fun and light read. The second, seventh and tenth books all have major Classical elements, and the seventh is one of my favourites, but I'm recommending this tenth volume as a really interesting representation of an ancient Roman character thrown into a modern context. If you haven't read any of these before and just want to give them a go the second book, Living Dead in Dallas, might be a better bet.
8. Poseidon's Gold, by Lindsey Davis
This is the fifth of Lindsey Davis' Roman detective stories told by private investigator Marcus Didius Falco. This story is lighter than the first few and stands more or less alone, and is set entirely in Rome and Capua - no descriptions of wet and cold Britain or Germania here! It introduces Falco's father, a lively character, and features a plot revolving around stolen art and antiquities and is generally a good read and a pretty good introduction to the series if you haven't read any before (the first book, The Silver Pigs, is the one I think is the best, but doesn't reflect the slightly lighter tone of some of the later books so well).
7. The Day Aberystwyth Stood Still, by Malcolm Pryce
This is the latest entry in another series I'd recommended among the geeky beach reads. Not actually science fiction and fantasy, Malcolm Pryce's Chandler-esque pastiches set in the Welsh seaside town of Aberystwyth are perfect if your type of beach holiday leans more towards windy walks on pebble beaches and bracing gales (as my childhood holidays did) than sand between your toes and bikinis. The downside is you'd be skipping to the end of the series, but the Classical parallels in this story - which features a Welsh Hercules and katabasis ice cream - are good fun.
6. Arms of Nemesis, by Steven Saylor
This is the second full-length novel Steven Saylor wrote about Roman detective Gordianus the Finder (two volumes of short stories are set between the first and second novels, and he has now written two prequel novels). It's set around the Bay of Naples, which was a popular holiday resort for ancient Romans, so it makes great holiday reading, though the plot is pretty heavy in places. As only the second novel written, it doesn't require much foreknowledge of Gordianus or his family, so it's a pretty good place to jump in, though of course, the first novel to be written, Roman Blood, is equally good - but includes more Cicero. For me, that's a bad thing!
5. The Song of Achilles, by Madeline Miller
I have frequently compared The Song of Achilles to Twilight, and I stand by that comparison. It's fan fiction of the Iliad (which I suppose makes it 50 Shades of Grey rather than Twilight itself, but I haven't read that). The descriptions of Achilles are ludicrously over-done - I know, in the author's defence, that he is literally a demi-god but I don't think we need to hear how gorgeous and god-like his appearance is every five minutes. Two thirds of the book are teenage romance, followed by a final third in which it finally gets to the Iliad and gets really quite good. But, as I've said before, I read and enjoyed Twilight, which does what it does perfectly well, and I enjoyed reading this, too. The easily flowing writing, sweet romantic theme and, in the last third, fast-paced action make this a perfect beach read.
4. The Charioteer of Delphi, by Caroline Lawrence
All of the Roman Mysteries make great beach reads and I have, indeed, read several of them on a beach (or boat in Croatia, as the case may be). They're perfect for a holiday in Greece, Spain or Italy - appropriate setting, short length and fast-paced since they're middle grade books, hinting at a darker reality but keeping the tone reasonably light, again, because they're aimed at child readers. Most of them can be read independently of the others as long as you don't mind spoiling a few plot developments, up until The Slave-girl From Jerusalem, after which the last few books do need to be read in order so you can follow the story arc. The Charioteer of Delphi is the last truly stand-alone of the books before that final group, and the conclusion is one of the most satisfying of all - plus it's got exciting descriptions of chariot racing, which would have been my favourite sport if I'd been an ancient Roman (looking back at my review, I know a lot more about sport than I did when I wrote it, and about various motor sports in particular! I'd totally have been into chariot racing if I'd lived in ancient Rome). My absolute favourite of the books in The Gladiators from Capua, but for a slightly lighter summer read, this is the one I'd recommend.
3. The Hunger Games, by Suzanne Collins
OK, so this may not entirely answer the 'light' qualification, I confess. In fact, the first time I read it, I stopped after ten pages and had to be persuaded to continue by the hearty recommendation of OldHousematetheRomeone, because it was too depressing. But as soon as I got to the end of the first chapter I was hooked, because it is very fast-paced, making excellent use of the ancient technique of writing in the vivid present in a story on one of my favourite themes, gladiators. If you want something you can really get stuck into to the detriment of paying attention to anything else while you're on holiday, this is a good choice (and I can add, from personal experience, that hanging around Birmingham airport for hours on end is a considerably less frustrating way to start your holiday if you have this to read).
2. Metamorphoses (The Golden Ass), by Apuleius of Madaura
If you want to read something Classics-themed while you're away, why not read an actual ancient text? There are several ancient Greek romance novels involving pirates, kidnapping and main characters turning out to be African princesses, but I would always recommend this, the only complete surviving novel in Latin, sometimes known as The Golden Ass to distinguish it from Ovid's Metamorphoses (unfairly, I think - I enjoy reading this much more than anything by Ovid, Metamorphoses included. I don't care how beautiful his Latin is, I don't like his attitude). After a few isolated stories to kick us off, the main plot of the novel is about the trials and tribulations of Lucius, who is accidentally turned into a donkey while trying to turn himself into a bird. There's also a lengthy digression into one of the very few Greco-Roman myths with a happy ending. If you want some genuine and genuinely fun ancient literature to take to the beach, this is the one to go for.
1. Pyramids, by Terry Pratchett
Discworld is another series I recommended among my geeky beach reads, and there are several Discworld novels with a heavily Classical theme. The most Classics-y novels, conveniently, are both stand-alone novels that can be read alone without needing to know anything about the rest of the series, Small Gods and Pyramids (also Eric, a spoof of Doctor Faustus which, of course, features the Discworld version of the Trojan War, but which is a much shorter, illustrated novel and part of the Rincewind sub-series). Both are brilliant. Pyramids is slightly earlier in the series, but since neither are part of a wider group that doesn't make much difference. There are two reasons I've *just* given Pyramids the edge here. One is that Small Gods is heavier on the philosophy (both within the text, as in, it features philosophers, and as a reading experience) so for 'light' beach reads, Pyramids fits slightly better. And the other is simply that, though both are brilliant, I prefer Pyramids. If you've ever taken a British driving test, it's certainly a must-read, but even without that, it's a fast-paced, fun and occasionally moving novel, and a pretty good introduction to the Discworld if you haven't read any before.
Although, as you can see, I'm quite fond of children's and Young Adult literature, it's probably noticeable that there's no Percy Jackson on this list. I'm afraid that's because I literally tried to read Percy Jackson while on a beach a couple of years ago and just couldn't get into it. I ended up reading Michael Palin's Pole to Pole instead, which had a nice travel aspect even if not all of it fit the beach atmosphere! I'm sure I'll try Percy Jackson again some day.