We usually get hung up here on horror and sci-fi but of course there's other B genres -- 70s drive-in exploitation, for example....
I just finished viewing the first movie in The Cheerleaders Collection (The Cheerleaders, natch) and was pleasantly surprised at what a fun little movie it is! The nudity and simulated sex is just tittilating enough to be fun without being gross (a very fine line to be sure), the girls/women are all refreshingly natural (something you never see these days), and the movie actually has some real laughs -- especially in the last half-hour, which features one of the funniest on-screen football games since M*A*S*H (the movie).
Even the missus was able to watch it without wincing though she did bemoan the lack of any significant beefcake to vie with all the cheesecake (a sign of the times, I guess).
I've been on a quest to find sexy movies (not slasher thrillers, either) the wife & I could watch together -- up to now we've only been able to agree on Wynorski's Lost Empire (for me, though she enjoys the silliness of it) and Hercules In New York (for her -- though Arnold's win in CA has made it almost impossible for her to look at him anymore, poor thing). I think we've just found one more, and I would definitely recommend to couples looking for something a little retro, a little silly, a little sexy.
My personal favorite B cheerleader film is H.O.T.S., and if any man disagrees with me and denies sneaking out to the living room to watch this thing at 1 am on HBO in the early 80s after your parents went to bed, well, yer nuthin but liars.