We went in March with 2 kids, 5 and 7. There is a lot to do for a few days - we were there 4 days. The pool and slide are great and the kids loved the ocean. They have activities throughout the day for kids (arts,crafts,sports, etc.). You can rent bikes, tennis stuff and there is a 9 hole mini golf course by the pool.
We felt 4 days are about enough especially with kids because they might get bored.
Dodgertown is nearby if you are a baseball fan.
Have fun!