Trail Ridge Road through RMNP will not open til Memorial Day at the earliest. I think it didn't open til mid-June this year.

 

A few thoughts...

- The absolute best way to see Monument valley is to enter from the North through Mexican Hat. When I did that trip, Monticello was where I ran into serious snow. I also ran into snow in Bryce Canyon. My wife ended up with a minor case of frost bite on that trip. If you don't have heated grips or gloves: I strongly recommend them.

- There is a good chance that you will not be able to get through the Rocky Mountain NP. I was there in lat June/early July one year and there was still a lot of snow on the ground. It was cold and very windy. The pass is at 12,000 feet and there is a good chance it will be closed in May.

- Unless you are a big route 66 fan, I would skip Kingman and the ride through Peach Springs. There are much better things to see and roads to ride in that part of the world: Page (Horsehoe Bend, Antelope canyons), Painted Desert/Petrified Forest, and Chinle.

- Tip: Arches is an amazing place, but to see it you really need to get out and hike. Same is true for Bryce and Zion. The Grand Canyon is different for everyone. Personally, I am happy experiencing it from the rim, but I cant do it in less than 3 hours.

- Cool places to stay: Stanley Hotel in Estes Park (it's haunted), Cameron Inn (just east of Grand Canyon on the Little Colorado), Kanab Utah is great place to stay before heading to see Zion or Bryce.