I sometimes ride down to Sante Fe for work from Denver (and now the GSA mileage rate for bikes is the same as cars!) - as with you, the only TRUE road has two lanes, one in each direction (aka 'Blue Highways')....
I love going down via Wolf Creek Pass on 160, then on down 64/84 into NM... lots of options to get to 160... if you have the time, 149 from Gunnison is a blast!
Coming back out of Sante Fe, I like to sidetrack
285/68 to Taos - and instead head up along 503/76/75 through the mountains (Chimayo, Truchas, Penasco, etc)