Avengers v3 #77 ("Whirlwinds") is probably one of my favorite issues for the two of them -- it features Hank and Jan on vacation in Vegas, before Disassembled (so you can be 100% no one involved is a skrull) and has them using their size changing powers in bed. Seriously, there is a shot of tiny Hank walking up betwen Jan's sweaty breasts (lying on her back) that is just about the porniest thing I've seen in a comicbook.

The storyline that shows the infamous "hitting Jan" moment is Avengers volume 1 #212-220-something (this stretch of issues also includes the Red Thong issue where Tony's identity is revealed).

There's also a deeply cracky but fun storyline in early volume 3 where Hank gets split into two Hanks and there's Hank/Jan/Hank doppleganger pr0n (sadly, not actually) and Jan and Triathlon have to reintegrate Hank back into one person in order to stop him from disintegrating. The resolution, confusingly, is in an Avengers Annual issue and not a regular issue, so if you're reading through volume 3 Hank kind of magically goes from being slit into a manic and a depressive half to being all fixed between one issue and the next, and you miss the scene where Jan goes inside his psyche to fix him with her love (mostly by refusing to fix him and making him fix himself).