Just got back from WDW, and had one day of rain. Torrential, pouring rain. Things to think about: shoes that are going to function well while wet. if the attractions you are most interested in will close b/c of rain. if the other members of your group are going to be miserable if they get wet. The ponchos work well, especially if you have a backpack that needs covering, but buy them before leaving your hotel, as the lines will be long (and could be in the rain) in the parks. When you take them off when you get to an inside attraction, fold them so the wet part is on the inside, so you can carry them w/o getting yourself wet.
The rain we had lasted most of the day, on and off parts being very heavy. During those times, lots of puddles formed-my tennis shoes vent well, so dried quickly each time we went indoors, but DH wore docksiders (what was he thinking?) and his feet weren't happy. Heavy rain cut down on families with little kids/strollers. But, we were at HS, and Indiana Jones and Epic Stunt Spectacular close when it rains. Still wasn't enough to cut down on the lines at Toy Story Mania! though. Still didn't manage to get on that.
