If you like historical romance, no series (IMHO) can ever beat Diana Gabaldon's Outlander.
It's got a time travel element to it, which is always fun, but the characters are so well-developed and the research so well-done, that you'll never regret tackling it!
I loved it so much, I paid $35 dollars for an autographed hard cover of the first book, Outlander. Dragonfly in Amber is the sequel and there are 3 more after that!
Check it out!