NASA

First, if you're a spaceflight fan, there's lots to see!

There are a couple (still free?) bus tours. When you get there, go ahead and schedule. You don't want to decide to do one halfway through the day only to find out all the slots taken. There's usually one that goes to the modern pads (those still in use) and another that goes to the historic section where many of the Mercury and Gemini flights took place. Decide which is more your interest as I don't think you'll have enough time to do both bus tours (plus all of the other stuff there at KSC) in one day.

Tips:

• when you go to the Atlantis building there are two directions to go when you enter. The one you want is the long and winding ramp up (which is the left hand path from memory). The other takes you into the main room of exhibits. I won't tell you why (unless you really want me to), but take the ramp path first. It eventually goes to that same big room with the exhibits, but you really should see it in this order long ramp first, then room of exhibits. When you reach the main room of exhibits on the ground floor don't miss the solemn display of the remains of Shuttle Challenger and Shuttle Columbia.

• there is another building far into KSC called "Apollo building" or "Apollo center" can't remember exactly. This is also accessible by a free bus short bus ride, but I believe at least one of the longer bus tours ends there anyway. Ask the staff to be sure so you don't end up their twice. Its an awesome building, but your time is limited and there is so much to see! When you're in the Apollo building make sure to go to a section toward the from of the Apollo V rocket where there is a set of exhibits. Behind an unassuming wall are some pieces of Apollo 1.

• Lunch with an astronaut! Depending on the day you go, KSC may have an optional paid feature of "Lunch with an Astronaut" I've done this 3 times across 3 visits and have enjoyed them all. You'll be in a hall with a hundred or so other folks dining. The food is pretty good too. If you choose to forgo the Lunch with Astronaut paid experience, you can usually get a short presentation from them on Stage when they KSC does a Spaceflight News update (I can't remember their name for it). Its a small theater where they give updates on current crewed spaceflight missions and they'll usually have the Astronaut there before of after that presentation.

• There is an IMAX theater, and the films are usually pretty good, but they are usually accessible from other science centers and most of the other contents of KSC is not, so unless you really need to sit down in air conditioning for an hour, I'd skip this for more KSC content instead.

• In the left hand side of the IMAX building there is a bunch of stuff for commercial spaceflight, including flown a Cargo Dragon, a Starliner mock up, as well as a Dreamchaser mock up.

• Rocket garden - They free do spoken tour guides spoken tours several times a day. I really enjoyed these.

Things that are skippable if you're short on time:

• the IMAX movie
• the "shuttle experience" ride
• Heroes and Legends Astronaut hall of fame exhibit (its not bad, but there are much better things to spend your valuable time on)
• Mission to Mars (from memory its more geared toward younger visitors, but they may have updated it since last I saw)

Have a great time! If you have any follow questions, I'd be happy to share my experiences. If you're going on a launch day, thats a whole other ball of wax.