There are 2 buildings open to the public. The first one has the gift shop and ticket counter. There is an IMAX that we didn't visit. Generally the first building seems somewhat rambling. The second building is the Saturn V Hall and is centered around a Saturn V on its side. To get from the first building to the second.you have to go through the first building and walk across the Rocket Park which includes a vertical Saturn V.. There are good photo ops in the Rocket Park as you walk.
You could spend hours in the Saturn V Hall. Everywhere there are interactive exhibits, videos and gadgets to see and play with.
We timed it so we could have lunch there. This facility is a working research center and there are a number of full time employees so they have a nice snack bar that even has a salad bar.
We spent about 2 hours including lunch but could have made an entire day of it.
Their web site is here and the TripAdvisor reviews are here.