For seven days IN Colorado, here is what I would recommend:
1 day to get from Grand Junction to Estes Park
I-70 to US 6 (short) to CO 119 North to Nederland
72 North to 7 to Estes Park
The portion from 199 to Estes is called the "Peak to Peak Highway"
Then 3 nights, 2 full days in Estes Park and RMNP.
1 day to get from Estes Park to Gunnison, CO
Use Peak to Peak to get back to I-70 W to CO 91 @ Copper Mt.
@ Leadville, US 24 through Buena Vista, Poncha Springs
and over Monarch on US 50 to Gunnison.
Then 2 nights, 1 full day at Gunnison, Visit Black Canyon, Blue Mesa,
drive up to Crested Butte, Taylor Creek
1 day to get from Gunnison to Mesa Verde
US 50 to Montrose, US 550 to Ridgeway
then 62 and 145 to Cortez. 160 to Mesa Verde (short)
Then 2 nights, 1 full day to visit Mesa Verde
This could all be done in reversed order. Note that I have eliminated Great Sand Dunes because I think you need your seven days for these three stops AND because these routes: Peak to Peak highway and through Leadville, Buena Vista (Arkansas Valley and the Collegiate Peaks) will be a far better taste of Colorado.
Peak to Peak is a curvy, unlevel road but no difficult passes. Just a slow but beautiful drive. Monarch is the only major pass on this trip except on I-70 and it is an excellent roadway.
If you are interested I can give you much more information about this route and the places you could overnight. You may send a PM if you wish.