John - If you haven't already, you might want to look over another thread on this forum, the "Ca. destinations" thread, which has a bunch of discussion of a similar question, and may have some ideas for you.
The route through Italy Pass and the Bear Lakes/Feather Pass area sounds pretty good, but I would suggest you take seriously the suggestions some have already made that there is added risk involved in being in that remote an area with a group of kids. Not that I think your boys can't handle the physical challenges - if they are fit and motivated I'd say they can do it. The motivation is key. Also, 12 to 15 is a big range in terms of physical development - but you know that, and you know these boys better than we do. The risk is that in case of injury it's a long way to help, and you won't see a lot of other folks once you're back in there. Not that this should make your decision for you, but it's worth keeping in mind.
That said, I have another suggestion for you. I don't much care for the Pine Creek trailhead myself. I'd much rather go in over Piute Pass if I am heading for that area. A trip starting at North Lake, over Piute Pass, off-trail into Humphreys Basin, over the ridge into the head of French Canyon (with a summit of Four Gables along the way - easy walk-up and fabulous views), a little exploration of the lakes in French Canyon or Royce Lakes, then back by trail down canyon to Hutchinson Meadow and back up to Piute Pass and out might be a good option for you. You'd have some off-trail stuff, but not be quite so deep into the range and not be as far off the beaten path in case of trouble, plus I think Piute Pass is an easier first day and a nicer hike IMHO. And I think this is less talus and more slabby granite than going the Italy Pass/Bear Lakes way, which translates into more fun. Or you can do the same loop in the opposite direction, which may be better in terms of acclimatization.
I'll also suggest an idea I put forward on the other thread - Blackcap Basin, coming in from Wishon Reservoir on the west.