I worked at Philmont for ten years, and have been involved with hiking and backpacking for much longer than that.
Here's what I'd look for in a knife for Philmont:
1) Lightweight
2) Inexpensive. With that many people, things sometimes tend to "walk off". And kids always lose stuff.
3) Locking
4) A lanyard and/or bright color.
I don't believe Philmont allows Scouts to carry fixed blades.
Serious backpackers, on Philmont and everywhere else too, carry Swiss Army Knives more than any other product. The tweezers and scissors often come in handy.
Personally, I carried a BuckLite for a couple of years, and then upgraded to an Opinel for working, living, and hiking in the Philmont backcountry.
Victorinox Recruit ($13) would be a good one if you're considering a Swiss Army Knife.
The AG Russell FeatherLite ($35) is an excellent choice if you want something more 'modern' looking.
There's a new line of Outdoor knives from Opinel discussed here:
http://www.bladeforums.com/forums/showthread.php/929625-new-Outdoor-Opinel