Funny thing about the Bolero: Everyone thinks it's about an orgasm but Ravel himself was apparently asexual. We have no idea who, if anyone, he slept with. In the annals of the Secret History, that means he was probably gay.
Which doesn't mean Ravel's music has to be devoid of visceral physical energy. But his most characteristic music often is. I think of Ravel when I recall Yeats's description of Keats looking at life "through a sweet shop window." In most of his work, Ravel has a childlike delicacy. He also has the perfectionism of a consummate pastry chef.
Personally, I don't advocate listening to classical music during sex, since I already think too much. But if I did, I'd choose Ravel's piano music long before the Bolero. People describe the Bolero as an endless climax, but I'd say it's closer to being endlessly repetitive. Whereas the piano music is liquid and sensitive, which fits a couple's changing rhythms.
Also: I think the kind of music one picks has to do with the particular partner, mood and level of alertness. Downtempo is good for certain sleepy encounters, but for a woman who wants to feel heavenly about getting hammered allegro vivace, I'd choose vintage LTJ Bukem or something a bit newer (Total Science, for example). For women in their mid-to-late thirties, I've found Vampiros Lesbos to be OK, as well as Transient Waves and the soundtrack to Gil Occhi Freddi Della Paura. (Some used to ask for K&D and Thievery, which was frighteningly mundane, but like any hypnotized bachelor, I appeased them nonetheless (mostly with Matthew Herbert).) Monolake's Cinemascope and Gravity can be good for mechanical encounters, though I just saw a not-younger woman last week who couldn't take Monolake's "repetition" (read: grim dryness), so I played Casino vs. Japan instead (equally repetitious but brighter and lighter). The best cut for my purposes: "Ionized." There's something pleasant about feeling a comb filter rise through you slowly during the act.
And of course there are times when you want no music whatsoever, just something to drown out certain frequencies. In which case I'd choose the completely arhythmic: Nuuk, or Permafrost. And sometimes you want nothing playing at all, especially when your partner is talkative and has a great accent.
What I can't have playing are male vocals of any kind. I don't even think I could keep it up listening to male hip hop -- which is perhaps one of many reasons I won't get the chance to know Asia Argento.
OT: I thought I should mention certain films that have proved fruitful as preludes to musical or a cappella encounters: Dellamore Dellamorte (aka, Cemetary Man), by Michele Soavi; The Night Porter.