I think it is rare to have buddies that go camping with you a lot. Extended Family, maybe. If you go to places that other kids are at, let your kids find them! As poster above said, the kids will introduce the families. You go meet them, they come to you.
If you are outgoing, you will find friends for the stay. Usually it is over when one of you leaves.
Repeat next time. You get to meet LOTS of great people, in all walks of life, from all over. Great.
But, YOU have to be open to this. If you just keep your kids in your site, and stay there yourself, NONE of this will happen.