Just in time for Valentine's Day, I ran across this list, published about a year ago, of the best (in their opinion, of course) romantic comedies of the decade. I love movie lists that include at least a few things I've never heard of (which is, unfortunately, not that hard to do).
Some of the titles recommended are Greg Kinner's Ghost Town, Woody Allen's Vicky Cristina Barcelona, Virginia Madsen's Sideways, and Richard Linklater's Before Sunset.
But check out the whole article -- the descriptions are very good, and they're all very appealing.
Do your tastes run to classic films? If so, there's a bunch of romantic classics ideal for Valentine's Day. This article echoes a lot of my sentiments, especially in recommending Mr. Smith Goes to Washington (and other Capra films, like Mr. Deeds Goes to Town), and The Philadelphia Story.