Our crew deviated to Lost Creek Wilderness SW of Denver and Maroon Bells - Snowmass Wilderness near Aspen (bear canisters required, which they picked up at an REI on the way). The only issue they had was the Scouts had bags good enough for Philmont (40F) but not higher elevations, but the leader didn't discover this until they were already at Maroon Bells. Oops. Thus, they just base camped in West Maroon valley and did days hikes for a few days so they were close to "escape" if necessary. Still had a great time, but if they had known the equipment issue beforehand they would have just done a loop in Lost Creek, which is similar elevation to Philmont, instead of just an overnight to acclimate. This was mid June so nighttime temps were cooler on avg than in August but you can hit below freezing any night of the year above 10k in CO.
I would also suggest the Wind Rivers near Pinedale but that's a decent drive from Denver. It's my favorite spot so far. I went there yet again to watch the eclipse on the Continental Divide. :)
Anyway, if you want to hit something in CO/WY then make sure everyone is prepped for temps as low as 20. Also stay alert to Inciweb for wildfire info as you may need to deviate again! CO had a low snow year so things are pretty dry and there are fires all over the state. The Winds had pretty decent snow so they should be OK until Aug or so. I could offer some route suggestions if you want to go to any of these areas just let me know how tough you want and how many days.
FWIW, any backpacking in CO/WY will be superior to Philmont. What you miss is all the programs at the camps (and the extra expense LOL). You'll need to learn to do a proper bear hang without the advantage of having the cables in place for you already. One other skill you need is how to find good campsites for a group. In some places it's a challenge to find a nice spot for 1 tent let alone 4-6 so you need to know how to read topo maps well for clues and pick out tips from trip reports you can find.
Also, is your crew larger than 10? That will throw a wrench in things since most wilderness areas don't allow more than 10 without a permit. You could split up into two smaller crews if you have enough adults and hike a loop in opposite directions.