When we went there last September, the trainer told us that the weekends are the busiest. But they only allow a certain number people in to make sure that it doesn't feel over crowded and that the park retains the "relaxing" environment. So either date should be just fine.
Thanks for the replies! I think I'll go with the Sat because it is right in the middle of our trip and a break from the crowds over at wdw will be good.