Dang! I just got back from a lesson where I rode a Percheron mare... I'm kicking myself for not taking pictures. I have been wanting to for weeks, and here stands someone who actually needs them!
I will say that drafts are just like any other horses under saddle. They are somewhat limited when it comes to endurence (no twenty mile canters for these guys!) and heat toleration (at least the Percheron I ride is), but they are great to work with. Good horses; I've found they aren't the sharpest crayons in the box, but still an absolute joy.
Plus, riding such big horses makes your butt look smaller!