We have not driven 17, but did ride the Cumbres & Toltec steam railroad several years ago. The rail crosses and/or parallels part of 17 along the way. The road looked to be a good road then. There appeared to be one fairly steep climb soon after heading out of Chama when crossing Wolf Creek, but not for an overly long distance. Don't know about the road grades near the passes.
But as Thom02099 said, 285 to Alamosa and 160 to Walsenburg are both good highways. On 160 heading toward Walsenburg you will cross North La Veta pass. Not particularly steep going up eastbound, but steeper going back down. Just watch your speed going down and it will be no problem.