We camp host in Carbondale, CO (in between Glenwood Springs and Aspen) ever summer. 70 generally is ok mid April but you never know what will happen on the front range (Denver side) and Vail pass. Climbing from Denver to Vail Pass is approx. 80 miles and the first 40 some miles are a pretty good grade to the Eisenhower Tunnel. You're going from 5,280 (Denver) to 10,000 feet +- (Vail).
After vail pass it is pretty easy driving and once you are west of Glenwood Springs it really no issue at all headed to Moab. After the grizzly creek fire last year, Glenwood Canyon can be dicey depending on weather. So much burned that a lot of rain or any run off causes slides and can shut down 70.
I personally would not go before mid April and would also have chains. Commercial trucks are required to have them until I believe mid May.
2018 North Point 377RLBH, Roadmaster Comfort Ride, Dexter E-Z Flex Suspension, Flexair 21k Pinbox
2017 Ford F350 Lariat CC DRW LB 6.7, Air Lift 7500XL with Air Lift dual channel wireless