One normal one: "What Happens in Vegas" (with Ashon Kutcher and Cameron Diaz). Your typical date movie; starts off poor, picks up for about 45 minutes and then the jokes cease as if by magic for some weird reason, and it becomes more of a pure romance, rather than a romcom. Anyhoo - it's ok I guess, so I'd give it 3 Squids if I could use this board properly behind my employer's bastarding firewall.
Alternative choice: Perhaps if your date is a little on the naughty side, take them to "Forgetting Sarah Marshall". Can't remember the cast (sorry!), although some have familiar faces - but don't let that put you off. It's brilliant, if a little crude (as in lewd and rude!). If you're ok with that then get yourself to the cinema asap and watch it. My eyes were wet with laughter during a few scenes, and some may make you feel a little uncomfortable (but in a funny way) - esp. a full-frontal male nudity scene early on - that had the whole cinema rocking. The male body can be a funny thing indeed. Go see it. I'll give it 4 squids and some leftover calamari.
Forgetting Sarah Marshall sounds intriguing. I may have to rent it at some point. I don't get out to the movies that much these days but I did like Kutcher's Butterfly Effect and Diaz is da bomb as Mrs. Shrek.