If you are combining a historical with fantasy/SF and are aiming at some type of romance, you might look at Fangs, Fur and Fey which is written by a group of paranormal writers.
http://community.livejournal.com/fangs_fur_fey/
To get a broad overview, go to a bookstore and see for yourself what's in the section. You might also look in the Romance and Young Adults sections since they include a lot of fantasy as a mixed sub-genre.
Don't have a bookstore close? Visit Amazon.com and the online Barnes and Noble and do the above search. You also should goggle for SF/fantasy blogs and professional organizations. Another, place to look is the agents who accept fantasy/SF blogs who often mention their likes and dislikes.
It's a lot of research, but if you want to sell what you write, you must know the market where you sell.
Above all, heed Kitty Pryde's advice: "medieval-setting, tolkien-grave-robbing" is dead, dead, dead ... until someone can come up with a new twist on the buddy quest to save the world. The odds are this person is not you or me. But, then my first three books (unsold) are about elves.
Good luck.
