Moab or Durango/RMNP?

We just did portions of your trip this fall. I notice you took Custer State Park out in your last itenerary. We're hikers and bikers, and Custer was one of our favorite parts of the trip. Its beautiful and so much less crowded than the national parks. Harney Peak trail is awesome. We camped at Stockade North - it was great.
Badlands can be done in a day. We spent one night there and did all the short hikes, as well as the ladders trail.
Staying in 2 different areas of Yellowstone is a good plan. Up by Gardner is a good location for touring the north. Fishing Bridge is a good location for seeing Old Faithful area, and the falls area. Fishing Bridge Campground is awful, but hopefully you are just using it to sleep. We stayed a week and thought it was too long. We both got tired of the crowds, and had seen enough thermal features after about 5 days.
We thought Colter Bay was great, but we lucked out with a really really nice site. The Tetons are beautiful. This was probably my favorite part of the trip.
I agree Estes Park is a tourist town. Didn't float my boat. The Rockies are amazing, but very crowded. As most places we went, once you hiked a mile in, the crowds thinned out considerably.
The hard part of advice is everyone likes something different!
Enjoy making those great family memories!

agesilaus wrote:
1) I think most people dislike the campgrounds in Estes Park, I suggest looking on the west side of RMNP for a CG
2) I would go south from RMNP and stop at Great Sand Dunes, it will be a big hit with your girls, a day there is plenty. Camping there isn't a bad idea tho since you can see the dunes early and without the thousands of foot prints that will appear later.
3) I'd go west from there and stop at Mesa Verde, make reservations online for a couple of tours. They will be filled up if you wait until you get there. Durango is a possibility if you want to take the train ride. Might make reservations for that too, online.
4) Turn south at Cortez and go to the North Rim of the GCNM which has much smaller crowds and the view is just as good in my view those some will argue about that. It's nice and cool too. If you stay in the park make reservations early. Otherwise you'll camp in Jacob Lake at a FHU CG. But that adds a hour long drive into the park.
5) Head north stops at Pipe Springs NM (an hour or two) and Coral Pink Sands SP might be considered.
6) Do Bryce (nice and cool) and Zion (hotter than hades) next. You'll see all the red rock you want which will make up for skipping Arches.
7) To break up the long drive north you might add Capitol Reef (more red rock) and Dinosaur NM (big hit with the girls).

Make sure to make reservations for Yellowstone as early as you can, you want to stay at Fishing Bridge CG and schedule a week there if it fits in you schedule. You can't see the place in that period but you see a lot of it.

In the Badlands you'll want to look at Rushmore ( an hour or two) and stop at Badlands (daytrip). Stay at Custer (reservations) and a stop at Wall Drugs outside Badlands is worth the stop. It's a tourist trap but a first rate one.

Think about a drive thru of Custer NM going back east, I found it surprisingly interesting.

There are probably 50 small parks and attractions along this path that you can use to break up the drives. Get a good map and look at nps.gov

I think this entire post is dead on. I would avoid Estes Park. It was our least favorite stop on our recent 2-month trip. Access RMNP from the other side. The only thing that I would add is that of all the mountain passes we were on, I would not hesitate to tow on any of them with a modern truck with engine braking. However, do not tow on the million dollar highway if you find yourself in that area...Ouray to Silverton. I won't even drive that section again...big drops right off the fog line, with no guard rails or shoulder. Towing it is certainly doable, and I saw it done, but it isn't for me.
Enjoy the trip. If you have the time, consider going up through Canada and back via The Michigan upper peninsula with a stop or two.

Of course I would disagree with NR over SR of the GC. You only see about 10% of the GC at the NR. Same reason I could put up with the crowds at Estes Park. There is very little to do or see of RMNP from the west side. I lived in EP for 8 years, left in 2003. We would never go there again now! Too many other good places.

Utah Hwy 12 is awesome and don't pass up the hike to Lower Calf Creek Falls.