It is about 2 hours driving. There are a couple different routes you can take that can shorten or lengthen that time. We have only flown into Orlando(MCO). Though the last 5 years or so we have taken the train from Va. If you're wanting to go to VB first I know some people fly into Melbourne (MLB) which is about 40 miles away and then there is Palm Beach (PBI) which is about 80 miles.
They absolutely have a lot for kids to do at VB. Here is activity sheets for last June