I'm not a big fan of medieval romance. Too much violence, the position of women was not good, and the plumbing was seriously grim. But when I was working out my "subversion of the captivity fantasy" novel, I chose a medieval setting for Uncommon Vows because in a more civilized era, my hero would be considered psychotic. <G> In the 12th century, he was instead a powerful man who behaved within the parameters of his age.
A lot of research was involved because I didn't know much about medieval living. I decided that I wanted to catch some of the flavor of an age of faith, where the Roman Catholic Church informed every aspect of society. Europe was bound together with a unity of belief that ended with the Reformation.