We visited KSC this past June. DH has always wanted to go there. My son (12) loves science, so he enjoyed it. They really enjoyed the visit to the Astronaut Hall of Fame (right outside the KSC complex). They had a couple of simulator rides there.
We bought the passes that allow you admission to pretty much everything. We enjoyed the bus tour a lot more than I thought we would. I had heard that it is a long ride and very boring...but we didn't find that to be true at all. The bus only travels short distances between stops. At each stop, there is a movie, museum, or exhibit for you to visit.
The only thing we were disappointed in was the food. It was not very good and the prices were higher than WDW. You are at their mercy because you are not allowed to bring anything into KSC and you are miles from anywhere else to eat.
It only took us about an hour to get there from Orlando. The roads are well marked and it is very easy to find your way. Be sure you have lots of change for the tolls and be sure you have enough gas. A lot of the trip is through a wild marshy area and there are no exits for miles.