Should have mentioned, get a MTB, kids have a lot of fun when they're guiding you through the woods even if they start with the bunny trails.
We killed time while the cooks did their work. Kids started with 16" wheels with knobby tires and I went with a cross bike, so you could go CV style there with a classic cross. With 20" I could still get away with cross but it started to get rough as they got bored with the easy ones. With 24" wheels like he's on now I had to have a true mtb. We're riding one of the hardest parks on Long Island and we hit most of the hardest trails there.