Anytime anyone here on the DIS asks a question about park shoes I nearly always jump in to recommend Teva Mush flip flops. I have several pairs in different designs. They are the most comfortable shoe I own. I made the mistake once of wearing tennis shoes down there and was miserable. I also usually take a pair or two of Crocs, but always wind up in my Teva Mush. I just love them. Another very comfortable flip flop for WDW are the Montrail Molokini's. They too are wonderful and feel like you are walking on marshmallows. Reefs, Nike and broken in Havianas are also OK, but not as comfortable as the Teva Mush and Montrail Molokini's.
The only flip flops I've ever had any trouble with down there are the Reef Ginger and Teva (Ulani, I believe they're called) with the little narrow ribbon toe post. The Teva Mush and Montrail Molokini both have the wide soft ribbon for a toe post.
Oh, yes I am definitely a fluffy Pooh!