You mentioned going to REI in Pittsburgh. If you are in the Pittsburgh area, head up I-79 to Sharon, PA. There's a shoe store there called Reyer's. It's 36000 sq ft of shoes, and they specialize in hard to fit feet like ours (I wear 15EE). Not affiliated or anything, just a happy customer.

Another option is Benny's Boot Hill in Bridgeport, WV. If you want to go the mil boot or work boot route (I wear Thorogood work boots when hiking, and get them at Benny's) they carry them and can handle odd sizing/fitting. Plus they'll generally have boots you can try in stock.

One other word of advice from someone who lives in his boots.. look for boots that can be resoled, rather than boots that have soles that are molded to the uppers. They are made better and generally fit/break-in better, they can handle insoles or orthotics better, and when the time comes, you can have them resoled. Just my .02, ymmv.

Jeff