I'd stay off those unpaved roads in the Rockies with anything less capable than a Jeep, unless you know specifically where it's going and what it's like. Some of them have some rather tight, narrow switchbacks plus, as Tom says, they can be mighty rough on your rig. Some of them can, with little warning, become 4 wheel drive only part way through, too. Even some of the paved roads are not much fun in an RV. Trail Ridge Road (U.S. 34) is basically an east/west road and, though it's basically a nice road, has some places where you'll be white knuckling while driving that class C -- a couple of spots I'm white knuckled in my F-150.
For Glenwood Springs from Estes if you use Trail Ridge, I'd either take U.S. 40 East (it goes south from Granby) to I-70 then west or U.S. 40 West from Granby through Kremmling to Colorado 134 West to Colorado 131 South to I-70, then west. However if it were me in my Ventana (38 foot DP), I'd take U.S. 36 East from Estes to Boulder (avoiding Trail Ridge in my RV), then Colorado 93 south to I-70, then west to Glenwood Springs.
However, though I know that U.S. 40 south from Granby is decent road, with only the Berthoud pass having tight switchbacks and steep climbs and descent, I've never been on Colorado 134 or 131, so perhaps someone who has traveled that section can pipe up.
Addendum: Looking at Tom's link, I see "partially paved and hard-packed-dirt mountain drive that has amazing views and breathtaking hairpin turns" as part of the description. I'd avoid it.
