Before my trip in September, I tried on all the Teva/ Keen's I could find (LL Bean, Sports Authority, Dick's, Bob's, etc.) and all of them were much too narrow. I was looking for the kinds with adjustable straps, not flip flops. I do not consider myself as someone with freakishly wide feet - I buy wide when available, but usually just wear a normal width a half-size up.
Then I started looking at Fit Flops, which were also much too narrow. I had to go up 2 or 3 sizes just to get my foot in! It was laughable.
I ended up buying a pair of Nikes that LOOKED like all the Teva's I had tried on, but ran wider. I was never able to get them from "instruments of torture" to "broken in" so they are still in my closet. THEN I bought a pair of fake Fit Flops (from K-Mart, of all places) that gave me all the support of real Fit Flops and were very easy to break in, with the help of some band-aids between the toes.
I alternated between my good sneakers and Fake Fit Flops at Disney and didn't have a single blister.
Good luck to a fellow wide-footer!