Come to Colorado and stay anywhere that the elevation is 7.000 ft. or higher!
Old mining areas like Leadville, Creede, Silverton, Telluride-Rico, Lake City, or Crested Butte stay cool at night and are very comfortable, and SUNNY, in the daytime. Those towns are generally high enough in elevation that you would not always need hookups because you will not need AC. And, if you do, it does not automatically mean you will need a private RV park. Nearly every state park campground and, these days, even some Forest Service campgrounds in the Telluride, Durango, and Marble-Redstone areas have electricity.
Touristy areas in the mountains like Pagosa Springs, Glenwood Springs-Aspen, Steamboat Springs, and Estes Park can also be very comfortable, but crowded and fairly expensive, so you will likely need reservations in advance. And if you prefer to be very near a big city, try Cripple Creek, a 10,000-ft. high mining town turned casino resort just west of Colorado Springs and Pikes Peak.
So, take your pick based on your interests--exploring old mining camps on jeep roads; fishing, kayaking, or rafting mountain rivers; climbing 14,000-ft. peaks; swimming in the world's largest outdoor hot springs pool; riding a lift to the top of a ski mountain; sitting in front of a slot machine; or a little sampling of each.
Of course, I'm not sure why I'm posting this under "Canada"?