Not a fan of sexin' to rock or metal; I normally end up pumping to the beat and that's no good, particularly if a) it's fast or b) it's in some odd time signature. I normally go for ambient these days, Eluvium's Talk Amongst the Trees, Belong's October Language or Tim Hecker's Harmony in Ultraviolet.
Alternatively, if my lady friend does not enjoy ambient, I might go for some rock with some irritating or masculine male vocals. Think Aerosmith. Just because I'll get so unaroused I'll take ages, and seem like a sex god.