Tires are an exercise in compromise. You can help the situation by throwing more money at it, but that's the nature of the thing.
You want reliability but that means more weight. More weight is more work.
I have used Marathon Racers. They are pretty rugged for their weight. They are also lighter than the other tires you mention, and quicker.
As far as size goes, it's your call. 35c is a typical size for a touring bike. It's a good choice. Btw, you might want to call Schwalbe as some of their tires run large and some run small.
The 30c Racer actually says 28c on the tire (and is 28c). I have heard the Supremes run a bit large, give them a call and ask them which tire is best for your kid. I found them very helpful when I called.
I am fascinated by the Supremes. They are light for a touring tire, and would prob get him across the country without a single flat. It's what I would pick. In 35c they only weigh 45 gr more than a Racer. By comparison, a pair of XR will weigh nearly a pound more than the Supremes.
Last edited by late; 04-26-08 at 10:49 PM.