No music comes to mind for me for a long sweaty night or a hot and heavy scene, but piano music does it for me for romantic evenings. Aside from ragtime, most anything that has a piano as the featured instrument will have the right feel, I think. Start with Chopin, and work from there.

In the opposite vein:
I would say that "Puff, the Magic Dragon" is the worst possible music for either the sweaty or the heavy purpose, but then someone would prove me wrong. In any case, avoid it. If, by some horrible miscalculation, it does come on, DO NOT TRY TO IGNORE IT. Stop, change the music, then continue. Trust me.