Two words: Duct Tape.
I'm a large guy, 350lbs, and it took me two days to develop almost incapacitating blisters on my feet in WDW. I was double socking (thin sock inside thick sock), but it didn't help.
Then, I learned how to duct tape my feet. At first, I was skeptical, but I'll guarantee you, if you duct tape properly, you will NEVER get a blister on your feet.
Marathon runners tape their feet. If it's good enough for a 27 mile run, it's good enough for an 11 mile hike back and forth through WDW.
The main idea is to get the areas that normally develop blisters. When I tape I put one piece across the ball of my foot, about an inch up each side, across the bottom. Then I use one piece on the heel, going vertically from the back of my heel, down, and over the bottom, to my arch. Then, I use another piece going horizontally across the back, making a cup on the bottom of heel, covering each side of the heel cup. That's normally all the tape it takes, 3 pieces per foot.
I use the cheap webbed kind you get from wallyworld, and I also shave the hairs on my feet to make removal a bit easier... yes, I'm THAT hairy.
And, we carry a roll with us in the park in case we need to retape. I have pictures somewhere of a retape session, but it's my wife, and I don't think she'd like it broadcast. Security doesn't even ask what the duct tape is for.
CM have asked us and said it's a great idea, when they see us retape. Sometimes, it takes a few days to 'get it right'... you know, you might think it's seated right, then something starts rubbing, and you have to correct or live with that blister the rest of the trip.
So, shoes for pain, duct tape for no blisters.