Re: Rocky Mountain NP to Moab Utah along the Colorado River ?
We were impressed with the I70 Canyon route, mostly the engineering feat of putting an interstate on/beside/over a river the size of the Colorado, with very little flat ground to work with on either side. Nice scenery there, too. I wish we'd had the stamina to keep going to California. We bailed after visiting Las Vegas, and retraced our steps back home. We were just exhausted, but had found some really nice places along the way, for future trips. Our original intent was to get to LA and then do the coastal highway north to Vancouver BC, then the Trans Canada highway home. Oh well, maybe next time.
It's not a sprint(er) (unless you make it one), it's (hopefully) a marathon.
RV - 2018 Navion 24V + 2016 Wrangler JKU