when my kids turn tv on it defaults to family list. there's about 65 channels on that list max (including sports, movies, etc). they don't even know we have all these other random channels. during football/basketball season i use my "sports" list at times to access games easier.
we get a few channels that have questionable content...those are blocked and require a passcode only my wife and i know to watch. so even if they figured out how to access regular guide ("all my HD channels" for example) they wouldn't stumble upon anything we don't feel comfortable with.
we also have very strict rules about when the tv can even be turned on, what has to be done before it can be turned on (chores, homework, sports/exercise, piano, etc) and how long it can be turned on.