The crowds should be lower in August at WDW because most families have gone back to school. Yes, it will be hot, but you are in Florida, so that's to be expected. DL in October weather can really vary. We were there this past year. We had a few days super hot, then it dropped off and it was quite nice. The evenings get chillier, in my opinion, because they don't have the humidity, so you still need a jacket. If you go during MNSSHP, it can get pretty crowded from all of the locals there. You will have a magical time in both places though--you are going to the Happiest Places on Earth! Enjoy!!