Soarin' you're asked to leave them on the ground in front of you. Sum of All Thrills in Innoventions they ask you to leave them on the platform before you get in the simulator. Other than that, there aren't any other attractions that require you to remove them that I can think of. I will say that removing them for Space Mountain is a good idea. I have the worst time getting out of the car in flip flops. Oh, and if you want, you could always take them off for KRR and put them in the center storage area if you want to keep them dry.