With your limited time, I wouldn't head as far as Glacier. Pick a few choice places, park your rig and explore. You have a big rig which really limits the campsites available in the NFS and NPS systems. Are you amenable to boondocking? If so, let me know and I can help you out with some ideas.
Specifically thinking about your kids and what they would like, I'd suggest some of these places. (Family travel should be 90% about the kids and 10% about the adults!) I'd stick to the CO/UT area, maybe with a trip up to Yellowstone (more on that later).
Recently, someone else from FL with kids 10, 8, and 4 asked the same question. Check out my answer ....
Since your kids are a little older, let be add some things to that post. In CO, for kids I always recommend the area around Salida and Buena Vista. Higher in elevation so cooler. Ghost towns, river rafting, biking, fishing, hiking. The Arkansas River Valley is around 7000' to 8000' or so with 14000' mountains all along the west side. Go as far north as Leadville (at 10,000') rent bikes and ride the
Mineral Belt Trail around the town, passing many old mining buildings and relics. Cool mining museum in town too, if you get a passing rainstorm and need a place to hang out for a few hours. Rafting on the Arkansas is some of the best in the state and has something for everybody, from relatively easy to pretty hairy. Spend a afternoon or evening exploring downtown Salida. Interesting shops, array of great restaurants of all types and costs, a river wading right though to town where the kids can wade, and on weekends there's often free music in the park. As for places to camp, most of the NFS CG's are under the reservation system and are full. Even those that aren't under reservations have few places for such a large rig. Do a search here under "Salida" or "Buena Vista" for ideas. I know some like the KOA in Buena Vista.
In the Durango area, your rig will fit in some sites at Mesa Verde NP CG. Not quite dinosaurs, but quite interesting to kids nonetheless. Sign up to take one of the tours where you have to climb some ladders -- that will get the kids talking. In the same area, we often camp at McPhee Reservoir NFS CG. Some sites have electric hookups. Usually doesn't fill. The nearby
Heritage Center is worth investigating.. What ever you do, I think a ride on the Durango - Silverton train is worth doing, although you may have trouble getting reservations at this late date (just be flexible when looking for dates -- sometimes there are cancellations). Riding a narrow gauge steam train through amazingly high mountains to a real honest to goodness old mining town is something your kids won't forget (and neither will you).
I didn't mention Dinosaur NM in the previous post. Green River CG in the park does have some first come first served spots that will fit your rig. No hookups, but flush toilets. There area a couple of state parks north of Vernal that have some sites with hookups. Check to see if any are still available. Or head up by Flaming Gorge reservoir and camp in a NFS CG. Much cooler up there. "Commute" down to Vernal to do the dinosaur thing. Besides the NM, don't miss the dinosaur displays at Utah Field House in Vernal. Well worth the time (I'm a geologist -- I wouldn't mislead you!)
Yellowstone -- really tough to do with such a large rig on such short notice. You might find some reservations outside the park at this late date but you should do a search here to see what CG's people recommend and check to see if there are any spots available. It's much easier to find a spot in Grand Teton NP as there are many more sites that are first come, first served that will fit your rig.
Ken & Allison
2 Camping Cats (1 diabetic)
1996 4Runner, TRD Supercharger, Edelbrock headers
2007 Fleetwood Arcadia, Honda EU2000i
4 mountain bikes, 1 canoe, 4 tents, 8 sleeping bags, 2 backpacks
(You get the idea!)