This place is so huge, make sure you plan a full day for this.
There are two tram tours to be done and lot other things to be seen on your own.
Starting with the Starship Gallery, where loads of artefacts (both real and high fidelity models) are on display covering Apollo, ISS and Mars missions, you can move into the Independence Plaza where the SCA (actual) and Independence Shuttle (high fidelity model) are on display. You can take an insider tour (this is the Orbiter Tour).
Then there are the options for two tram tours (you have to choose one only) where they will take you on Astronaut training centre (Red Tour) or the Mission Control Tour (Blue Tour).
There are two gift shops for your merchandise hungry soul, a decent cafeteria, kids play arena with simulation models etc.
Suggest to take an audio tour guide as it helps a lot if you need to boost your nerd self right upto into space with al the info!
Reach early as soon as they open, choose timed tickets for tram tours while booking tickets online and visit the Kemah boardwalk while returning!