I think the MK is pretty good in the rain. All the rides/shows are pretty close to one another.
We did Epcot on the pouring rain once. We went from the monorail station to The Land so quickly because there was very little covering.
We ate dinner, stood outside & then ran back to the monorail.
But I had my then 15 mo old dd with us. If it was just me or dh & I, I wouldn't be as concerned about getting wet.