Have been to Orlando, but not California park. We took Airstream to Ft. Wilderness RV park. Really enjoyed it. Until they kicked us out, as Hurricane Jeanne was headed our way. Have been back several times for day trips as, it is only 2 hours from us. Bring plenty of money, especially if you are going to eat on site. 3-4 days and I am ready to leave a place like that. With kids, 5-7 days might be possible. Don't forget the Kennedy Space Center!

On edit: This was the end of September, and place was not very crowded. A good time of the year to go.