We have enjoyed staying at San Angelo State Park because of the natural things it offers. We stayed in the Red Arroyo campground. The sites are large and well-spaced apart. You don't have much privacy due to the lack of trees since this is where the prairie and desert come together, but the distance between sites helps. Also, having a picnic table and covered shelter at each site is a nice touch. 

One thing we noticed is that when the wind gets going here it really blows hard, so be prepared to take care of anything that might need to be held down. Several times it was bad enough that we had to close our roof vent. 

The night sky is decent because it's so wide open, unfortunately, it's not as dark as we had hoped because of the lights from nearby San Angelo. You also tend to hear some road noise -- it's not bad, just louder than we expected considering how this place seems like it would be in the middle of nowhere from most of the pictures. Given the expansive horizon, though, you're in for some really cool sunrises and sunsets right from your campsite. 

The hiking, biking, and equestrian trails here offer a lot of variety and with 50 miles of them, it's tough to get bored. Note that the North and South units have separate trail systems and there's no road within the park to reach the two units. You have to drive out on the main road and it's too far to bike or walk. 

In addition to trails, make sure you check out the wildlife blind set up near the Red Arroyo loop, plus on Saturday and Wednesday mornings, the rangers do supplemental feeding of the bison and longhorn cattle herds, bringing them right up to the fence for visitors to see. It's a nice treat! As you hike, you're likely to see plenty of wildlife, too. We have seen deer, owls, birds, and javelinas so far. 

Cell service was pretty good for Verizon and T-Mobile. (2-3 bars consistently) 

The only real complaint (other than tiring of the wind after a while) was that the bathrooms are really old. They are kept clean and the showers were hot with good, modern showerheads. But in Red Arroyo, there is only one shower for women and one for men for the whole campground. And there also are very limited toilets in the main bathhouse and the secondary bathhouse has at least one defunct toilet in the men's room. The whole park could use a bathroom/shower house overhaul. It hasn't been very busy with campers here but we could see that a busy season could wreak havoc on bathroom availability. 

Note that if you're coming for O.C. Fisher Lake, that is a reservoir that is emptying out and never likely to come back. A ranger told us the lake is at about 6-8% of its glory days. The place is filled with boat ramps to nowhere and when hiking you can find several abandoned campground loops. 

All-in-all a good place to stay but go in with your eyes open.