I think radio is ok, but there are probably better ways. Radio is funny because you have to chose to either market to one of two demographics, kids, or parents. Saturday morning TV would be better If your local stations even have available slots! The networks usualy use up those slots with cerial and toy ads. I've always thought that a great way to use tv would be to put some sort of kids variety type show on cable access(based around camp). 6 or so :30 episodes in the spring. Look at the effect "Bug Juice" has had.
I like camp fairs if you can find away to divert the constant flow of kids to your table. Some kind of giveaway is the best, I saw a camp buy flats of bottled water and slapped thier own lable on it.
