It's been a few years, but I can tell you that I-70 through the Colorado Rockies is some of the most scenic highway in the country. West to east you'll have a long but manageable upgrade approaching Vail Pass at about 10500 ft, then down to about 7500 or 8000 before climbing again to the Eisenhower Tunnel at about 11,300 or so, and then it's the looooong gradual downhill to Denver.
It's a lot of altitude, but the whole road meets Interstate standards, so no excessive grades, no scary drop offs or sharp hairpins.
Of course, that 250 miles of unbelievable scenery has a price, and that price is that after you pass Denver and head out onto the plains you've got 800 miles of Kansas and Missouri in front of you!
John & Diane, Fulltimers. RVM103 NHSO
On the road since June '12 with Lincoln, the guard cat.
2002 Dutch Star 40, Freightliner, Cat 3126, 2004 Element