I 70 or I 80

I-80 by far. I-70 is to prone to freezing rain because of it's further south.

 

I'd just take 80 into Nebraska then take I76 into Denver then get on I70 and ride out to Grand Junction from there. That's the fastest way and you won't hit any "hills" of any consequence till you get west of Denver.

 

I don't know if you anything about I-70 in Colorado but a lot of truckers try not to use unless we really have to because the Mountains are just way to big over there but not like it's something impossible. You will most likely get hit with snow and ice. It is the fastest way to Grand Junction but you be the judge. One is for sure it is one amazing sight to see up there!

 

Those are not hills, that's one hell of a mountain especially in Feb HAHA

 

This +1 I-80 Roll On

 

Yep, I-70 west of Denver to grand junction is a reall, reall beech for truckers this time of year especially. Wont be to bad in an suv though. Do give yourself plenty of time, try to bring some extra cash and make sure you got your camera. Thats some of the most brutal interstate any trucker will drive on, its also some of the most beutifull interstate most will drive on. You will want to plan to leave Denver early in the morning, and plan on stopping and taking lots of pictures. Take the time to pull into every rest area thats open while going down glen canyon. There is one every mile or two or three.