I loved The Other Boleyn Girl and then The Boleyn Inheritance by Philippa Gregory. I read all the books in the series, but these 2 were the best. Love the relationship between the sisters in the former, and the latter has a great character in Catherine Howard... such a teenage girl!
I agree The Help is a good one... some of it is so similar to the film that it's basically word-for-word but the whole book isn't like that, and more goes on so it makes some parts in the movie make more sense.
The Guernsey Literary and Potato Peel Pie Society is a good one as well. Funny bits, sad bits, lovely bits... just a good book generally.