An hour from Orlando along a toll road (about $4) ...

An hour from Orlando along a toll road (about $4) and on the Atlantic coast of Florida, the KSC is a full day out with enough to interest and entertain everyone from the science nut to those with only a passing interest in the space programme past and present. $20 to park with a short walk to the centre. Bear in mind the site is in the coast, so winds can be cooling compared to Central Florida.
KSC has a main centre and a second that you visit after the 45 minute bus tour to the launch pads that's included in admission. With knowledgeable drivers, this tour shows you the launch sites, both active and historic, along with some of the nature in the area (KSC is a huge nature reserve).
The site the tour takes you to is a tribute to the Apollo programme and features a full Saturn V rocket along with information about all the missions, especially Apollo 8 (the first 20 minutes is a show about this) and a touching tribute to the astronauts lost in Apollo 1.
Back at the main centre, the showpiece is Atlantis, in a fabulous exhibit hall about the shuttle programme and the dedication to deliver this.
With other areas showing current work, plans for Mars exploration and the beautiful rocket garden, this really is a full day out that's worth it.