Forgot to mention, once you get to Denver, there is no real way of avoiding it, you will get on 70 for abit but take the exit to Golden & take the Clear Creek Canyon up to where it joins I70 a little east of Idaho Springs.
A really spectacular ride & quite a shock for any flatlander.
Golden is worth a stop if for nothing else the Coors plant. There is a mountain ovberlooking the town that can be driven up to. Stunning view on a clear day. Fillup before you leave Golden. The altitude & price of fuel do nothing but go up from there.