Although I grew up in Utah, “state park” was a bit of a mystery to me. We camped in local National Forest campgrounds and visited the popular National Parks, but my only experience in memory with official State Parks were trips to Goblin Valley every few years. As we first started traveling, I was a bit wary of staying in any State Park (we had a bad experience in Omaha) but after passing through a few states with some amazing experiences (Georgia, Texas, and Florida to name a few) I was able shift my paradigm and really come to appreciate all the work and effort that goes into maintaining these beautiful places!
With this shifted mentality, we made it a point to visit a few of the local Utah state parks on our Southern Utah Sanity Trip (as we are now calling it). Many we had heard good things about, and since we had the time we made a point to weave a (slow) path through Yuba Lake State Park, Fremont Indian State Park, Sand Hollow State Park, and Snow Canyon State Park.
Yuba Lake State Park
Our first stop was recommended by friends. It was not a very long drive on our first day, and the views were beautiful. We managed to level the Airstream despite a 9 inch side to side elevation difference thanks to a small shovel I threw in as an afterthought. It was incredibly peaceful. The lake is frequented by boaters, and there really wasn’t much else to do, but it was a peaceful spot with good signal.
Fremont Indian State Park
We continued south to a spot in the middle of Fishlake National Forest. The campground was dry (no hookups) but had plenty of sites big enough for our Airstream. Surprisingly, the signal was great. We explored the area around the campground and enjoyed the petroglyphs and pit houses at the visitor’s center. As we were staying over a weekend, we rounded out our Sunday activities with a trip to church in Marysvale, UT, and a drive over the mountains the other way to visit Cove Fort, and LDS historical site.
Sand Hollow State Park
After two boondocking spots, it was time to enjoy some time near civilization. Sand Hollow Reservoir fit the bill nicely, with some great swimming, paddling, and sunsets. The kids loved playing along the rocky shore and swimming from ‘island’ to ‘island’. For the older and more adventurous, there are some popular jumping rocks as well. We rented a kayak one evening, and enjoyed a bit of a paddle.
Snow Canyon State Park
We loved this park so much, I wrote a whole post on it. Playing in the sand dunes, hiking, and exploring. Plus its only 15-20 minutes away from a fairly large town. We had the pleasure of sharing this stop with some of our family, and had a great time. I imagine this park is often skipped over in favor of larger National Parks like Zion and Bryce, but those folks are making a mistake. Their loss was our gain, as we loved enjoying the beautiful rocks and wonderful views.
We loved these parks! The kids are already asking when we can go back, and although it will most likely be awhile we would definitely love to visit them again. We culminated this particular adventure with a trip to Zion National Park, but that will have to wait for its own post.
2. Go for a bike ride. Cyclist, or not, both the paved Whiptail trail and the road through the canyon make for great bike riding. With our kids, Sam dropped us at the top near the Upper Galoot Picnic area and we rode down to the sand dunes where he picked us up. We also had my family with us, so we took turns shuttling and riding and generally had a great time. Since the road goes through the canyon south to north, you could actually do a loop ride if you wanted something a little more serious.
4. Scramble on the rocks. Climbing on the rocks near the campground is not permitted, but there are designated areas where kids of all ages can scramble over the fun rocks. Scrambling is permitted at the Galoot Picnic Areas, Whiterocks, and the Petrified Dunes. All over the Galoot Picnic area are these small, rounded pebble rocks called marbles. 
5. Go for a Hike. There are plenty of hiking trails in the area – most are not dog friendly so just be aware. Johnson Canyon is closed to the general public from March 15 – September 14, but you can sign up at the visitor center to hike in with a ranger. There is very little water in Snow Canyon and their rules protect what little water there is and preserve it for the wildlife.
6. Earn a Junior Ranger Badge. Snow Canyon has its own State Park Jr. Ranger badge that the kids really enjoyed, or if you are visiting other parks in the area there is also the Junior Desert Ranger that encompasses Snow Canyon, nearby Coral Pink Sand Dunes State Park, Zion National Park, and Sand Hollow State Park. As we had just left Sand Hollow, and weren’t aware of this activity book, we decided we’ll save that one for the next time through.
7. Visit St. George. Surprisingly, the smaller city of St. George is quite bustling. There is a splash fountain in the downtown area next to the Mormon Tabernacle for your kids to cool off, or if its super hot (like it normally is in the late spring and summer) stop by Iceberg for a delicious, ginormous thick milkshake. I’ve also heard Pioneer Park is very fun with lots of rocks to scramble over, but we didn’t have time to stop there. They also have a Costco in nearby Washington, outlet stores and other shopping.
You can’t camp right on the Salt Flats, but the speedway borders some BLM land and we just pulled off there for the night before continuing into Salt Lake City the next morning. 
The speedway is definitely an impressive site, but probably only worth the stop for the photos– unless you go during 
Muir Woods is definitely a beautiful place. I can’t wait until we can go back and spend a bit more time exploring!