If AJA is driving on north from Phoenix, this is an excellent suggestion. There is tons to visit and do, fantastic scenery and history. Durango-Silverton Railroad is a suggestion.

I recommend Steamboat this time of year. Lots of shops and restaurants. Drive up in the mountains. Shalet at top of ski mountain. Wyndham Timeshare rentals available. Hunting and fishing available through local outfitters. Not very crowded this time of year. Rest and relax. You fly from Denver to Hayden, then drive into Steamboat about 20 miles.
Good luck.

Living in a rural part of NY and far removed from any of the big metro cities we are just laid back folks avoiding all the hussel and bussel. We have gone south on numerous vacations. FL, Memphis, New Orleans, Nashville. We have gone west, CA, Las Vegas, TX. About 25 years ago we went north up to Maine. No planes and just a long drive but very scenic through VT and NH. We have gone back to Maine almost every vacation since. Coastal Maine is very nice but can get rather busy but nothing like the congestion's out west. Interior Maine up toward Greenville, Moosehead Lake and Baxter National park is nothing less than eye candy and some of the nicest folks in this country. Sea Food to die for and north and west Maine are drop dead gorgeous places to visit and much less expensive than any other place we have ever been.

If you want to get out of the 110+ heat, come to Las Vegas. It's only going up to 109 today. :-)

Not really much to do in Denver besides watch a lot of people sit in traffic (in my opinion), Boulder is nice, I would recommend Fort Collins and Colorado Springs as well. Get a rental car, see the sights.

Weather report for Estes Park CO https://weather.com/weather/today/l/U...

Rocky Mountain National Park is an awesome drive. Check out if there's any concerts at Red Rocks in Morrison (just outside of Denver) as it's a stunning place to attend a concert! Boulder is just a little to hippie for my taste...but if that's your cup of tea, I guess go for it...

PS: Fargo, ND (my hometown) is a great place to visit, especially in the Summertime. Sunny & 76 here today...Take that Phoenix!

If you go to Colorado, go to Colorado Springs. Better things to do and more to see. The People's Republic of Boulder is nice as it is up near the mountains and Denver is down in the Platte River Valley. Both places have lots of things to do. I lived in the Denver area for a number of years and I called it home for 22 years while I was floating around the world while in the Navy. It has grown and the area did not keep up with the infrastructure needed to support that growth. The new pot boom has further stretched resources and infrastructure. Rents and property values are ridiculous now and getting worse. The good thing about any of the cities is the vicinity to the mountains.

AJA,
I as you may know live in Grand Junction. unless you really want to engage in lots of traffic go to the Denver boulder area. and its mass of people. there is significantly more to see and it is certainly more beautiful on the western slope.
my recommendation is that you enter the state on 160 going to cortez and stop at mesa verde. from there head east and north many mining towns one I recommend is creede. from creede north to lake city is a road that I think as the most beautiful in the state, it is truly the high plains, at 12000 feet.
after these areas look at your map and where to go, like the great sand dunes, etc. enjoy.

Denver is one big sprawling mass of humanity and the last two times I've been through there freeway traffic was stop and go. That said, here's one of many websites with some good suggestions as to amusement parks, theaters, festivals, etc ... https://www.denver.org/things-to-do/.
Grew up in Phx, It certainly was a different place back then (shot doves with Dad in the stock yards between Phx and Tempe) but can commiserate re: the summer weather.
Have a great vacation.

Are you locked into Colorado? I left home in Phoenix the first of June to avoid the heat and I am now in Colombia (South America) watching the weather reports in Phoenix and smiling.

If you go to Boulder, check out Pearl Street. Mrs. Animal and I enjoy a sunny Saturday afternoon on Pearl Street, laughing at the hippies.

We have a half-way decent system in Colorado, you see; we keep most of our hippies in Boulder, and Pearl Street is pretty much ground zero. The problem places like California have is that they let their hippies wander around loose. We keep them in Boulder, with small enclaves in Aspen and Nederland, and most of the rest of the state is blissfully unbothered.

Watch out for drum circles.

Weird, I figured there would be more folks from Colorado among the membership.

Yes, we've driven to Salt Lake City and visited Zion Park on the way back. Frankly, if I limited mytravelings only to places that agreed with my philosophical view I'd have very few places to go. I couldn't even visit my birth state, NY.
Colorado is a neighbiring state we never visited.

NM and Colo both supported Obama and Hitlery. Colorado was a Ted Cruz state on the GOP side.
BTW, Hitlery won Colorado because of large wins in Denver and Boulder. She also won in city of Colorado Springs, but lost that county to Trump. He did well in southern, more rural areas of Colorado.
https://en.wikipedia.org/wiki/United_...

Have you visited southern Utah? I'm thinking about visiting there on my return trip from west coast to east coast. How about Idaho? I spent 6 weeks there on business (many years ago) and enjoyed every minute of the low humidity and cool nights. Don't know about festivals there except for the Snake River Stampede.

I don't have too many limitations, though I tend to favor things to do (amusement parks, theaters, festivals) rather than nature trails and hikes (my wife's forte. I tend to like trying out new things rather the doing the same things over and over and over and over...etc.

This is why trip planning is rough for us. It usually starts with a tug of war (her wanting San Diego and the beach AGAIN) and me wanting to explore.

and yes, after 25+ years in Arizona it nice to get away from the state from time to time. In all these years we've never visited Colorado or New Mexico.

I don't have any suggestions on that area, but you might want to elaborate on what you enjoy doing to get better suggestions from others with more knowledge on the area.
I guess you have had your fill of cooler temps of Sedona, Payson, Flagstaff, Prescott, Wickenburg, Grand Canyon, and (standing on the corner in) Winslow, Arizona.
Colorado went to Hitlery (and Obama twice.) Why give them your business? It's time for a consumer strike.