I have extremly wide feet 12 EEEE
The only shoe really on the market is New balance, and I am not crazy about them. There styles have gotten a bit better over the years, still not the greatest lookin shoes. I tried some asics extra wide but after 3 weeks I tossed them, not comfortable at all.
I am also flat footed, and developed a problem with my feet because of it called planar fascia, basically I am in constant pain with both my feet. I tried several doctors about 10 cortizone shots total just in my right foot, orthodics, to this day I am still in extreme pain. It's weird how it came on to, I just went to get out of bed one morning and went right into the wall next to my bed (from the pain stepping down)
I am also looking for a good pair of slippers (the only wide width I found is lands end, they only last about three months and are pretty exspensive for a slipper), I know most guys probally don't wear them but I don't have a choice, I can not go barefoot around the house anymore according to the last doc I went to, and he is right if I walk around the house barefoot, the pain is allot worse.
Edit::
I had a pair of Berkinstock, they were terrible till broken in, took somewere around a 9 months befor I could wear them for more then a few minutes. I still may look for another pair evantually the ones I had wore out.