I feel your pain. We were there today as well, in our many many trips to DL, we have never been rained out....we were out of the park by 6. My youngest is 1 and was not a happy camper. We sat for the parade and it was cancelled. They had the "Rainy Day Cavalcade," instead....which was not very exciting.
It sounds like its a good thing we left, we were going to head over to Freeze The Night in the evening....it would not have been worth it to stick around and not see Marshmallow!