The main thing on the passes is to use your transmission for braking and your brake as little as possible. (Feel free to use your exhaust/engine brake all the way down!) Most passes are about 8-10 miles in the climb and about the same for the descent. We always used third out of six forward gears on the ascent and descent. Keeping the RPMs on the high side on the climbs will help keep the engine cooler. Rule of thumb is you go down at the same speed (and gear) as the climb, assuming you are not flying up the hill!
On US 550 south from Grand Junction you will experience the ride of a lifetime! The road is fine as long as you stay between the lines! There are no guard rails on the tricky spot just south of Ouray, but that beautiful section is the worst part of the whole drive and is less than 5 miles of thrills. The speed limits are very accurate for your needs in your coach. Good luck and enjoy our part of Colorado!