Just spent a week there over spring break. Awesome!! I had reservations and when I had arrived, I asked if I could change my spot. I was given a choice of campsites, but I had to choose one before I could set up. I picked one and had the other open site numbers with me in case the other site was better. I did chang sites with no problem other than going back and having my car pass and post sign changed--super easy. I really wanted a lake site but none were available. Next morning several campers left the lake sites, so I rode my bike back to registration and paid the upgrade and changed my site--again super easy! There are really no 'bad' sites, unless you are by the dump station and trash area.
Lots to do in the area. Great bike/walking trails all over the campground and beyond. GSP has a new zip line to try--looked like fun. Went to Ft Morgan and found that interesting, including my 2 teenaged boys. Gotta go to Lambert's cafe to eat. Lots off food and fun. Be prepared for a long waits.
You will have a blast there--we are trying to go back again over the summer!!