giordanos.com is one of the best Chicago style pizzas you can buy anywhere, and the kissimmee location delivers.
(Although they may be heading towards bankrupcy

, so a backup option is good.)
Avoid any flyers if they get put under your door, they are usually a scam (give a cc and they give you no pie)
Actually, I think the Boardwalk pizza window is an acceptable pizza vs the normal Disney junk.. You can get it room service, but that may cost more...