I don't have any recommendations, but have you used or seen one of the Otterbox Defender cases?
They are VERY bulky. I bought one for my HTC Incredible and it was nearly 3x thicker. I ended up ditching it because it was just way too huge in my pocket.
I used an Otterbox Commuter series for my first generation iPad and liked it well enough. I've since sold my iPad, but I had a hard time finding a case that I really liked. Good luck finding one!