IDman wrote: If you stay on I-25 you won't get to Estes Park.
He means 36 from Denver to Lyons v I-25 to Loveland and then to Lyons. (but I'm sure you knew that.........)
As a prior 30 year resident of Denver area do the I-25 to Loveland route if you want quicker, or 36 if you want slower, more hilly and much prettier. Having done both, towing a 28ft 5er, I actually prefer the 36 route. :)