There are the normal Florida afternoon rains, then there are fronts where the rain sticks around. We are just back and we had 4 days of sun, followed by 5 days of rain, followed by one day of sun (it rained heavily late that day but it was our departure day). On the first three days the rain stopped by afternoon. On the second two days the rain really didn't stop. So, I give these tips with experience.
1. Do you get cold easily? If so, wear more clothes (longer pants, t-shirt instead of tank, etc.) Even if it is raining, the rides, stores and restaurants will have the AC cranked up as if it's 95 outside, and if your skin is wet, you will feel really cold.
2. Don't try to brave AK in anything harder than a drizzle. Here is what you can do inside: Tough to be a Bug, Festival of the Lion King, Dinosaur. Everything else is outside. Several of the restaurants only have outdoor seating.
3. Epcot World Showcase isn't much better. Lots of the fun of WS is wandering around, having a snack from a cart, watch the live entetainment. That's not so fun in the rain. Some of the live entertainment is cancelled and some is moved to a location that is hard to find.
4. I think that much of Epcot's Future Wold would be fine in the rain. There is a lot to do in each paviolion (except that Test Track would be down.)
5. Magic Kingdom is fine in the rain. There are so many rides that it's no problem to be indoors. Last week it was rainy in the morning and we were the second family on Dumbo. We rode the carosel, tea cups, etc...all the stuff we normally breeze by, because the place was so empty.
6. MGM is okay in the rain. The distances between rides are longer but there is quite a bit inside.
7. DTD is okay...you could spend a lot of time in World of Disney and the
Lego store.
Lastly, make sure everyone has at least two pair of shoes. We got caught in a huge downpour and everyone's tennis shoes got very very soaked.