We are considering going next April and wonder if it is worth taking almost 4 year old DGD, almost 8 year old DGS and then 5 adults? We would have to rent at least one car to drive over from Fort Wilderness and we have our own vehicle as well.
If any of the adults and/or the older child have an interest in space travel/exploration, I would say it is definitely worth it! We just went a few weeks ago over spring break and it was me, DH, DS10, DS7, and DD3. The complex is huge and there was no way to see it all in a day. That said, we went online and printed out their suggestions for families with kids 10 and under and that was really helpful. My 7 year old loves space and had a great time. He really enjoyed the exhibits and movies. They have an interactive game called Cosmic Quest that he thought was a lot of fun. They have different NASA missions in several of the buildings and you get hints at different portals throughout the exhibit and after you get all the hints, you try and solve the mission. Some are easier than others! My husband enjoyed playing with him and said it was a good way for him to learn about the different concepts in an interactive way. It's an extra fee to play, about $20.
The bus ride from the Center to the Apollo/Saturn V Center goes through a wildlife refuge. Be sure to have the kids sit at the window and look for alligators. We saw at least 5, including one that had to be 10-12 feet long sunning itself on the banks of a canal. It was my 10 year-olds highlight of the day!
(He isn't as into space.)
There really isn't too much there for the little one. My 3 1/2 year old was a little edgy, but we knew that could happen going in and I planned to stay with her so my husband and sons could enjoy the exhibits. There is enough to see just by walking around that I didn't feel like I missed out too much by not seeing the movies, etc. Our biggest mistake was forgetting our stroller. They rent them there for only $6 for a single, but they are the hard plastic ones like at Disney and she wasn't able to nap in them. As a result, she ended up napping on me in the middle of the Atlantis exhibit, which is a pretty cool place to be if you are going to sit on a bench for an hour!
The ride there is nice and easy. It's a straight shot and well marked. No problems there, just bring money for tolls! If you have a car, I'd say definitely worth it. If you need to rent a car just to get there, I guess it would depend on how easy that would be and how much everyone wants to go, etc.
One other tip, we found the best discount on tickets on the AAA website if you are members.