I really love Phillipa Gregory's books. She manages to take a well known period of history and make the reader see it in a completely new way. She obviously does a lot of research, and she stays accurate to history, but she gives a new perspective to the events and what might have led up to them.
I'm really enjoying the Cousin's War books, this is my second one, and I'm going to start another right away. I think it's very interesting to read about the same historical moments from very different perspectives. In a way it makes me question some of the assumptions that are always made about history.