I know the chances of me calling now and getting reservations from 4/14-4/21 are most likely out of the question. However what are you experiences from once I get down there, obviously I know I should try, but do people often times cancel? Does Disney leave x amount of spaces available still for walk ups? Lets say I wanted to go to the luau at the Polynesian, does that have a greater chance of having availability as opposed to the restaurant?