My family and I recently stayed at Rollings RV Park on Flathead Lake in Montana, and we loved it! Although it's all back-in sites for RVs and there's not a lot of room, we found that the park was beautiful and quiet, and the staff was very friendly. They have some tent sites and cabins available as well.
There's a restaurant on-site, but it has limited days and hours. The food was excellent, but it's like being in the UK, where you order everything yourself.
The park is clean, and the sites have a decent amount of space. You're close to Polson and Lakeside, where there are great beaches. The campground has its beach, but you have to drive to it.
One of the best things about the park is the great playground for kids. Our kids loved it!
The only thing we didn't love was the parking situation for guests or extra vehicles, but since it's a small place, we understand that it can be limited.
Overall, we will 100% stay at Rollings RV Park on Flathead Lake again and again. It's an awesome place, and we highly recommend it.