My wife and I are in the early stages of planning a road trip with our motorhome and tow car. We will be returning from the midwest and figure we will be near Denver around September 10. We need to be in Albuquerque on October 4 for the Balloon Festival. We would mainly like to concentrate on seeing National Parks: Rocky Mountain, Great Sand Dunes, Black Canyon of the Gunnison, and Mesa Verde. After that, I'm sure we will have more time to see some parks and sights in Utah and New Mexico as well. We like to sightsee, take photos, and hike, maybe 5 -6 miles per day.
Questions: How many days to allocate to each park? Any RV friendly sights in Colorado that are not too far out of the way that we are missing?

The first thing you should do is get a map and plot a logical route that includes the eastern Utah NPs. Arches and Canyonlands, Mesa Verde and Black Canyon of the Gunnison could be done in a loop at the western side.

Rocky Mountain and Great Sand Dunes are closer to Denver, but RM is north and GSD is south.

I would probably do Denver to RMNP to GSD to MV to either BCG or Moab (Arches and Canyonlands) then down to Albuquerque with perhaps a stop at Bandelier or Aztec Ruins on the way.

How much time for each park depends on how much you want to hike. That said, I would not want more than one day in Great Sand Dunes, would want at least 2 or 3 days in Mesa Verde (sign up for the ranger led tours), 3 if Weherill Mesa is open. I could do a week in the Moab area between Arches NP, Island in the Sky and Needles District of Canyonlands, Fisher Towers, and some of the other sites there.

I would not take the RV on the Million Dollar HW, but you could do a half day round trip from Durango to Sliverton or Ouray if you haven't had your fill of beautiful mountain scenery, in your tow vehicle.

Bandelier (near Los Alamos, NM) is worth a stop and you can camp there.

I can read this in two ways:
1) Starting on September 10th, you want to focus on 4 CO national parks but will have extra time to visit some parks in Utah and New Mexico after CO but before October 4th.
2) Between September 10th and October 4th, you want to focus on 4 CO national parks and will have time after October 4th to visit parks in Utah and New Mexico.

Big difference, so can you clarify?
If it's #2, then you have 24 days to visit 4 parks and get to Albuquerque. That's easy. Black Canyon is a 1 or 2 day park as there isn't much hiking unless you enjoy extremely steep trails into the canyon. Mesa Verde is at most 3 days so that leaves close to 20 days for 2 parks plus driving time.

If it's #1, then emalloy has a decent starting point for an itinerary discussion.

#1 - Starting on September 10th, I want to focus on 4 CO national parks but will have extra time to visit some parks in Utah and New Mexico after CO but before October 4th.

I can't wait to hear the replies - we'll be in the same situation come next summer and have similar interests. Maybe we should plan a meetup LOL!

I think the route emallory laid out works as well as any. Obviously, you need to hit RMNP and move south. By mid September you could easily encounter snow on Trail Ridge Road and on some of the other passes you would have to go over. Personally I would skip the Sand Dunes as it is just a unique pile of sand. It is a couple hours drive by at best. Very little to see and do there. The area around Durango and MV is far for interesting. If you skip the Sand Dunes the drive to the Black Canyon via Leadville would be far more interesting.

You have a great deal of time -- but there is still ALOT of driving involved to see the 4 parks in Colorado that you have listed. I have been to all 4 in the last two years -- so here is my take.

The two parks NOT TO MISS are RMNP and Mesa Verde. Having said that, we also loved Black Canyon of Gunnison. The Great Sand Dunes would be not only out of your way -- and good for a few photos and thats about it. So -- with your time, this is what I would do.

#1. Rocky Mountain National Park. Fantastic -- you could easily spend 3-4 nights here. Estes Park is an awesome town. The drive from Denver is fantastic over the Peak to Peak Highway. Stop in Boulder for a night if you would like to acclimate. The Flat Irons are beautiful and very cool little town.
#2. Trail Ridge Road (if open) to 70. You could either head toward Grand Junction/Fruita area to see the Colorado National Monument (another National Park!) or head south through Leadville toward Aspen over Independence Pass. In a camper pulling a car, I might opt to do the 70 to Grand Junction. We are doing this National park this year. On the way -- you will drive through Summit County. You may even want to stay in this area and explore. We love Frisco -- Lake Dillon -- Breck area.
#3. After visiting this area, I would head south through Montrose to the Black Canyon of Gunnison. Beautiful views -- great drive along rim. Only need a couple of hours to visit. Like previously mentioned, the hikes would be treacherous at this site.
#4. Travel on to beautiful Ouray or Telluride. Great stop, beautiful hikes/waterfall.
#5. Head down to Durango or straight to Mese Verde NP. We only stayed at the park for one night -- at the Far View Lodge. We took a guided tour that took us down into a dwelling. So cool. I would suggest 2 - 3 nights if you plan on doing extensive hiking.
#6. Head down to Albuquerque. I am so jealous! I want to visit the balloon festival next year!

Have a great trip! Hope this helped! . Colorado is so beautiful -- you may want to take more time to explore the small towns as you drive through as opposed to trying to fit in Utah this trip.