On our honeymoon, my wife and I stopped in Lassen Volcanic NP. We were blown away. So gorgeous. This was one of the only campgrounds open at the end of May. Most sites were filled on a Monday night. We did not have a reservation but I would recommend making one. The sites are right next to each other and there is not much seclusion. There is a pretty rigorous hike with a trailhead just down the road. We loved the park, and the campsite was good. FYI lots of pollen around this time. My white truck was yellow after the night. We were here in late may.