Comments on certain parts of your trip:
Day 1-4 – Drive to Grand Canyon
Day 5-6 – Grand Canyon NP (2 full days, Trailer Village Booked)
Day 7 – Drive to Lake Powell
Day 8-9 – Lake Powell (2.5 full days, Wahweap Booked))
Have you booked a houseboat? Even so, it will be very hot. Those I know who frequent Lake Powell just won't go there in the summer.
Day 10 – Drive to Zion
Day 11-12 – Zion NP (2.5 full days)
Try to get a spot at Watchman CG in the park. Right by the Virgin "River". Kids can play in the water, build dams, etc., while you sit under the huge Cottonwood trees and cool off. Make sure you hike up the Narrows. You might have to carry the youngest on your shoulders in the deepest part, but in August, the water will be low and the temperatures comfortable.
Day 13 – Drive to Bryce
Day 14-15 – Bryce Canyon NP (2.5 full days, Ruby's Booked)
Day 16 – Drive to Moab
Day 17-19 – Arches/CanyonLands/Mesa Verde NP (3.5 full days)
You really can't do Mesa Verde from Moab. It's just too far. Again, Moab is excruciatingly hot in August. We live three hours away and wouldn't go there that time of year. Might I suggest going to Durango instead. Mesa Verde will easily take up a day. Take another day and take the Durango - Silverton Narrow Gauge Railroad. Might be the highlight of the trip for your kids.
Day 20 – Drive to Glenwood Springs
Of the two pools, we think the old Hot Springs Pool is more fun for kids than Iron Mountain, which I would recommend for a romantic retreat.
Day 21 – Drive to Estes, CO
Day 22-23 – Rocky Mountain NP (2 full days)
Day 24 - Drive to Colorado Springs
If you take the above advice and go to the Grand Lake side, might I suggest heading to Salida instead of Colorado Springs. More to do, more to see, and MUCH less traffic to deal with. Great rafting, ghost towns, fishing, mountain biking, hiking, etc. etc.). It will also be cooler than Colorado Springs. It one of the places in CO we like to take guests when they come visit.