Queens I have always loved to read about include Boadacea, Marie Antoinette, Elizabeth 1st and 2nd, Catherine the Great and oh, so many others. What is the pull of royalty that makes a steamy book steamier, a life of luxury so much luxurious and the adventures much more exciting? I guess at the root it is money and power. These qualities are in spades amongst royalty. It is the 'Dallas' factor - even a bitch can be greatly entertaining.
Reading about the royals of Britain is fun as these days, the real 'facts' seem to be emerging. So many of the old Kings were Queens! There is a book about Marina of Kent which tells all. It seems to have been really well researched and I lent my copy to my uncle and he didn't ever return it so sadly, I cannot share the details here. It may have been by James Wentworth Day. He has written a number of royal books.
Anyway, regardless of the hair-curling horrors of the life of Catherine the Great, the book I read about Marina was by far the most fascinating.
Money and power sells and I guess it will always be like that.