Publisher's Weekly ran a nice article on readers of romance and the various subgenres. I think it's definitely worth a read-through, especially this comment by Shauna Summers of Bantam Dell:

If there's a catch in this ever-widening, perpetually cross-pollinating category, it's this: all this variety may have crowded out a so-called subgenre that was once the staple—contemporary romance. It seems that writers are so dazzled by werewolves and castles that a modern-day hero and heroine is simply not so common. “We're actively looking for stand-alone single titles, and we're just not seeing them,” Summers at Bantam Dell says. “Part of the reason may be that contemporary romance has cross-pollinated with women's fiction. In the books that come close, the tone, structure and focus of romance is hard to find.”