The stretch of I-40 between Memphis and Little Rock, AR, is notorious for its heavy truck traffic. I avoid it like the plague. After Memphis, AR, I would take US. 79 and US 270 to Hot Springs unless you are determind to stay on the interstate.
I have been on the Mesa Verde - Moab route recently and recall good highway and good scenery.
Like Thom02099, I wonder about doing all of this in five weeks. But enjoy the trip one day at a time. If you get it all in, fine. If not, you will still have had a great trip.