We did a 1200 mile loop from Santa Fe thru Utah and back to SF 2 months ago that covered most of your routes -- in a Tundra pulling a 32' TT.
Utah does an outstanding job of marking down grades with the % incline and just enough notice to downshift. Anything more than 8% for sure we went down in first with the flashers on and didn't have to use the brakes.
Be aware that this is very desolate country, especially in regard to fuel stops. The stretch from Blanding to Hanksville via Scenic 95 is one of the most gorgeous drives we've ever seen, but it is 144 miles between service stations and I don't think we saw 8 vehicles in that stretch. Plan a picnic or snack on the runway overlooking the bridge at Lake Powell - first left after the bridge if N bound.
We camped at Torrey and made a day trip to Bryce. Went down Scenic 12 which was beautiful but took over 3 hours to travel 100 miles, including a 10 minute stop for the cows to get off the road. We came back to Torrey via 89/62/24 which is not as scenic but a good road thru the country (and takes you past the only real grocery store in probably 100 miles at Lola).
Blanding and Torrey were especially nice towns. A bit Quirky, but very nice, neat, and friendly. We wished we could have stayed longer at both. Blanding has a first class dinosaur museum just a block off 191.
This was the best trip we've ever taken. Take your time and enjoy, but know where your fuel stops are. We found lots of stations closed and deserted, so plan your fuel stops where there are at least 2 stations.