If you want a slow, pretty route, you can take I-84 to I-80 to Highway 40 at Park City to Dinosaur. At Dinosaur, go south on Highway 64 to Rangley, CO, then south on Highway 139 across Douglas Pass to I-70 into Glenwood Springs. We've also taken both of the routes you mentioned.
2017 Melbourne 24k - 2003 Jeep Wrangler
2013 Premier 19FBPR; 2013 Rpod 177 HRE
2011 Aliner Sport; 2008 Little Guy 5-Wide
1980 Shasta 21; 1981 Coleman Tent Trailer
1978 VW Westfalia