Well as you may know, I like sexy girls (animated and real ones), and I like when sexy girls engage in sexual activity with males. I don't like any of that XXX nasty porno stuff though. R rated and below. Anyway, I've seen many many many many sex scenes (well, maybe not that many, but I have seen alot), and a good sex scene always keeps me coming back for more. Anyway, some GREAT sex scenes are in:
About Last Night (1986)
Blown Away (1992)
Nightcap (Tane McClure gets to do great sex scenes)
Hmmm, I'm at a loss for words. I don't know any others at the moment.