I have visited KSC before, but this was my first visit to the new Space Shuttle Atlantis exhibit. It was very cool. The only thing that could have made it better was to actually go in the spacecraft. They have done about the next best thing, which is have a flight deck mock-up available for visitors to sit in the commander and pilot seats or pretend you are a mission specialist working with the robotic arm in the payload bay. Several simulators are available to give one an opportunity to pretend to be an astronaut for a few minutes.
The Apollo Saturn V Center is also an awesome experience, which includes walking beneath the gigantic Saturn V Apollo rocket that took Americans to the moon. The huge multi-stage spaceship is on its side and covers more length than a football field. There is also a moon rock available to touch.
There are many other attractions, including the bus tour (which you must take to see the Apollo Saturn V), Shuttle Launch Experience and lunch with an astronaut. You can definitely spend more than one day visiting the KSC, but we felt like we saw the highlights in our full-day visit. I would like to go back and visit the Astronaut Hall of Fame, which is close and included in the price of admission.