The ones that I love have already been mentioned:
- Jude Deveraux - totally love her Montgomery/Taggert series, but I'm not a fan of the Forever & Eternity trilogy. She writes anywhere from old Scotland and before (Jura) to modern times
- Julia Quinn - My mom gave me a bunch of her books, and I devoured them
- Julie Garwood - Same as above, though I don't enjoy them quite as much.
There's a few others that I've discovered through Harlequin's Love & Laughter series and Duets, but my bookshelf is currently behind my Christmas tree, and I can't get back there very well. I did notice Susan Mallory, who had a triplet series that I enjoyed.