I like the rotating LCD. I like it lots, since I used to have something similar on the Sony F717. It is smaller, but I've got good eyes and that makes no difference to me. 4MP compared to 3.2MP isn't that much of a difference, at least not for me. They're both fine for posting on the web and for printing smaller sized.
Would you rather have a big LCD, and a better movie mode? A75 is for you.
A rotating LCD and 4MP, because that's crucial? A80.
Shouldn't be too hard - either way, you'll be happy with either of the two