Hmmm, I'd say both would be pretty comprable and good times to visit. Do you want go sooner or later?? I'd guess by late April Rivers of America should be filled so I'd wait till then.
If your wondering about crowd control, I would pick March over April. but the weather will be warmer at the end of April. hmmm. tough decision.
When can you get a better rate for the hotel?
Have a great time.
It is a tough choice! warm weather would be great. I think the food and wine festival starts in mid April (not sure how much crowds that brings in). Were DVC members and will use our points. The main thing is to try and avoid spring break!