The Mitford books are nice because they tell a good story with good character development, without the need to resort to vulgarity or sleaze. I guess that sounds kind of corny nowadays, but I sure didn't feel I was missing anything because there were no F-bombs or steamy sex scenes.
The house we rented for our Outer Banks vacation several weeks ago had a ton of books, and I read so many I can't even remember them, but given the choice, I'd pick a comfy chair and a stack of Ruth Rendell mysteries and suspense novels.
I too am a Ruth Rendall/Adam Dagl. fan. Also like Elizabeth George/Lord Linley-she only produces a book about every 2 years though-she does extensive research in England and it sure tells in the finished product.