I recommend, depending on the high of the boulder, descent, etc. to have one parent on top and one below spotting. We do this to make sure our kid doesn’t have a problem toping out and don’t do anything stupid once they are up there.
Every area we’ve gone to so far has been great with our kids. There are a lot of smaller rocks that you can feel comfortable letting your really little kids give a try.
You can get the beta for bouldering here at:
Specifically, we’ve climbed at Cabbage Patch, Gate Boulders, and Secret Garden.