I know you don't want to hear any of what I'm about to tell you, but nevertheless it must be said.
Day 1) Champaign IL to Glenwood Springs CO: 1180 miles. No. I don't care how many people you have, assuming you can cover 70 mph for 17 hours straight is simply unrealistic. And when you do eventually get there, you will be exhausted, cramped and out-of-sorts. This is not getting your trip off to a good start.
Day 2) Glenwood to Bryce: 465 miles. That's fine as a relaxed day's drive, but to plan on spending 3 hours in Arches and an hour in Bryce on top of that is too much, especially since you will still be drained from your previous day's marathon.
Day 3) Bryce to Vegas. This day is quite doable on only 5-6 hours of driving. So I guess my question is: Why are you running yourselves ragged the first couple of days if you can take a few hours from this day (and others) to make each day enjoyable rather than starting off on the wrong foot?
Day 11) Grand Canyon to Amarillo: 700 miles, again 12 hours is extremely optimistic and that would allow no time for the stops you list.
Day 12) Amarillo to Champaign: 940 miles!!! Sorry, this is simply not possible in 13 hours.
Look, your trip is quite doable in the time you have, but if you want to have fond memories of it when you're done, you have to cut out the death march drives and better allocate the time that you do have.
AZBuck