I like Holiday a lot. Cary Grant and Katharine Hepburn are very good together...you should also check them out together in Bringing Up Baby. Of course, with romantic comedies, I always think of Tom Hanks and Meg Ryan though they only did 3 films together...and I still haven't gotten around to watching one of those.
Next to horror, romantic comedies are probably my least watched genre. I only own two and they are 'Knocked Up' and 'Baby Mama' which I just got recently.
We have here a Romantic Comedy horror zombie flick
Pete, you know how you trusted me on Val Lewton? Why not think a little older and look up some classics and see what romantic comedy is really about? I've recommended The Philadelphia Story before, but also, pretty much anything by director Preston Sturges. Antares has recently reviewed Christmas in July, which is just wonderful. Possibly the most famous though is Sullivan's Travels. Any of these are gems.One I've caught on TV a few times and keep meaning to pick up is Barefoot In The Park with Robert Redford and Bridget Fonda. You could also consider The Apartment (both me and Rich have reviewed that one favourably on here).