Dole Whips are the best. You can find them in Adventureland at the Magic Kingdom, the kisok is called 'Aloha Isle'. You can also get one at the Polynesian resort, at the quick service restaurant, Captain Cooks'.
The best part about Captain Cooks' is that you get to make it as big as you want, for the same price as a Magic Kingdom Dole Whip. I made a pineapple/vanilla swirl that was about the size of my head. Then I wandered around the resort in the dark until I found the gorgeous sandy beach, reclined in a hammock, and watched the 'Holiday Wishes' fireworks for the first time.
My favorite is the pineapple/vanilla swirl, but there's three flavors: pineapple, vanilla, and orange. You can 'swirl' them any way you want. Other people really like the floats, which is any kind of the ice creams mixed with pineapple juice.