Family of 10, sea world/kennedy/DC help BUS

[8timesblessed]

We are staying for 15 days and planning to go to Sea World, Discovery Cove and Kennedy Space Center and Gatorland. We are planning those trips while we are staying at AKV. We will be 3 nights at BWV, 8 nights at AKV and 3 nights at BLT. We are wondering if it would be better to take the bus and how easy it is to get from Disney to any of these locations? Could we do it without renting a car?? 3 of the things are going to be done 3 days in a row so we could rent two cars but then do we need carseats?? Our kids will be 5,6,6 for the 3 youngest. Renting a 15pass van is alot of money so it was cheaper to look into renting two cars but then I saw the bus might be an option and I think my kids would like that.

Any bus experts out there??