We just started biking a few months ago and had some great child friendly trails near us (some hard ones but usually with few riders on them). But we will be traveling across the country for the next year and I am hoping to hit a lot of trails. However, I'm not sure if there are "rules" or expectations for having children on trails. My son keeps up fairly well but he is only 7 (almost 8) and still has to stop some. Can we take him on any trail? How annoyed would you be to have to wait for a family to get out of your way? We definitely try to stay out of the way. Do many places have someone I can call ahead of time to ask?
If it's public land, anyone can ride there, old or young, fast or slow. The trail does not belong to the fastest rider out there. As long as you aren't stopping in the middle of the trail, or especially behind corners or below jumps and drops, you are fine. Anyone who gets upset at someone taking a break, or riding slower than them, needs to build their own trail on their own private property, or compete in a time trail style race.
That being said, it's neither courteous nor smart to get in way over your head. It's one thing to walk a short difficult section on a long ride in the backcountry , but it's not a good idea to take the double black diamond at the bike park when you can barely hack the green beginner trail next to it.
I would look for easier (green and blue-green) rated trails, then read the description carefully. Some easy trails are wide and flat. That's boring for kids, they don't care about the scenery.
For kids look for rides that are: -Mostly singletrack -Don't have too much climbing -Are not to long -Are new-school, machine built 'flow trails' with lot's of berms and rollers