Off the top of my head, and checking a little on twg.com, Princeville you cannot walk, and Shadow Creek, Sanctuary, Paa-Ko Ridge, are all essentially unwalkable.
A lot of the top carribean courses you aren't allowed to walk, either, but I don't know which are considered "top 100" or not.
A lot of resort courses, the price includes cart, and I'm not sure what they'd say if you stated that you'd rather walk.