I heartily recommend anything by Lois McMaster Bujold. Most of her later works have some romance built in, and even some of the ones from her Vorkosigan series (which is usually labeled military SF) have romance.
For absolute funny romance, try A Civil Campaign (vorkosigan, available from Baen Books)
For more serious romance, her fantasy is best. Books from her 5 Gods series each contain romance, and while linked can be read out of order (but Paladin of Souls should be read after Curse of Chalion). On the other hand, The Sharing Knife series must be read in order to get best effect. (these are all from EOS books, so they're more expensive and drm infested.)
Other thoughts (all SF or fantasy): Linnea Sinclair has all romantic SF, so far they are all individual books, not a series. Some of Marion Zimmer Bradley's Darkover books have strong romance. Patricia Briggs has some werewolf books out that have fairly strong romance.
All of my recommendations have some romantic elements, but (at least to me) have the story as the main point.