I agree with the above for the most part. US 160 over Wolf Creek Pass is a good wide road, 2 lanes going up so you can stay right and take your time and not hold up traffic. And several pullout areas if you need to take a breather or cool down. But it is a fairly steep climb for several miles. And the pass is over 10,800'.
If it is simply the altitude itself you want to avoid, then you can take US 84 south at Pagosa Springs to US 285 just north of Espanola, and north on 285 to Alamosa and back onto 160 to the Dunes. That does add a lot of miles but may be worth it to you. You could also take US 64 to cut across from US 84 over to US 285 to save some miles, but that road is more winding than staying on 84 all the way to 285. Use google maps street view to take a virtual drive thru the area.
You say you do not want to go south, but there is no other real option if not the pass itself.