Pedro1010

We booked Kennedy Space Center through RC and it was great: https://www.royalcaribbeanblog.com/2017/04/10/excursion-focus-kennedy-space-center-your-own-tour
You can easily do it on your own, you just need to grab a ride back and forth.

When I took my son on an excursion on Christmas eve 2018, the cost to rent a car, then pay to get in, was similar to the non-guided excursion, so we went with the ship for simplicity. But if I wanted to do something else the same day in the area, I would rent a car. In our case we made it onto the first bus over, and the first bus back, so we did not spend a lot of time waiting. We were gone for about 7 hours. 

Are you doing this before , during or after a cruise?
If before or after, I do myself.  If during a cruise, I'd book through the cruise company just for the insurance and ease.  Although it is very easy to do without using the cruise company.