We have "family memberships" which basically means the parent is the member of record but the kid(s) has full operating rights on the layout at any time. This got around the issue of junior memberships. What we've found is that the kids are actually less distracted when operating and tend not to run red signals as much as the adults do. We have four kids that operate regularly, sometimes with their parents as well. In addition to that, we frequently let visiting kids run our trains.
One problem with operating in a club context is that command control is almost mandatory. This makes the trains expensive for most families. We often tout the risks and rewards of eBay to get around that.
