I like Becoming Jane, it's pretty damn funny, plus I can never resist a bit of James McAvoy. Also love 27 dresses (James Marsden, need I say more?), Bridget Jones is fairly entertaining, and of course, Confessions of a Shopaholic.
Manhattan, Annie Hall, Breakfast at Tiffany's, (500) Days of Summer (duhhh), Sabrina. Basically, the films that established the rules of the genre and the later films that set out to defy them. Not saying there haven't been some good fairly conventional rom-coms in recent years, but the genre tends to be mostly faff like Maid in Manhattan and most of Kate Hudson's career nowadays.