We stayed at the group campground. Individual sites are first come first served, but the group site can be reserved for up to 40 people. It's HUGE. It has your own private men and women's bathroom, a large wash bin, two fire pits, and two grills with covered picnic benches. It also has its own parking lot and entrance/road where you likely won't interact with other campers. Lots of trees to hammock and the ground is flat and grass. It's about a 2-5 minute drive from the visitor's center and several trail heads. I would highly recommend for large groups that want some privacy.
I was here for one night with my dog. They allow dogs in the campground, but not on the beach. I wasn't aware of this, so it's a big part of why I only rated it three stars. The campground was pretty bare and not the prettiest or most immersed location when it comes to Utah. But it was what I needed. I can't comment on the beach since I didn't go. I had to drive to other parts of the lake so my dog could join me. Bear Lake itself is nice and pretty large, but make sure you have a boat, SUP or some kind of water device or it can get boring quickly. People recommend their famous raspberry shakes and I would say for good reason. About an hour drive into Idaho is, in my opinion, the much prettier Bloomington Lake with a rope swing and mountain face backdrop. But the water can get pretty cold.
The park and campground are small and the camp sites are fairly close to one another, so it's likely that you will hear and interact with other campers. The campground is a short hike and even shorter drive to the goblins and the grounds itself is surrounded by red rock that you can climb and explore. I stayed in a tent, but there are yurts available as well. It's also about a 10-20 minute drive to Little Wild Horse and Bell Canyon if you're interested in slot canyons. Very family friendly. I'd also recommend the Goblin's Lair hike. My favorite by far in the park.
My husband and I got in late at night and something went wrong with our reservation to where they double booked our site. The grounds supervisor was very apologetic and helpful in arranging another emergency site since the campground was full. The campground feels immersed in the red rock of the park and felt private enough from the other camp sites. By the way, the stars are incredible. It was also convenient for us to wake up and do the full Devil's Garden hike (my favorite hike in Arches) the next morning. We didn't mind the drive to the site as you get to see the park and you can make your way back on the way out. I would definitely stay here again.