I have driven a variety of ways between SLC and Denver and prefer US40. Away from everyone, good variety of straights, curves, scenic beauty. WOT around Strawberry Reservoir, wide open country between Dinosaur Nat'l Monument and Craig. Speedtraps between Steamboat Springs and Rabbit Ears Pass. And if no one is holding you up on Berthod Pass (11,307 at top) that is a hill climb that will put a grin on your face. You may turn around when you get to the last hairpin outside of Empire and go back over again!
Or, if you have more time and want to give your car a high altitude test break off US40 and take 34 to Trail Ridge road, America's highest continous paved road (peaks at 12,183 feet) - must do some time in your life. Lots of curves from the town of Grand Lake (feed marmots out of your hand at the Lake Grandby pumphouse) through Estes Park (home of the Stanley Hotel - "all work and no play makes Jack a dull boy") to the sculpture haven of Loveland.
Plan the trip so that entire section can be done at daylight at least until you hit the interstates again as you near Denver.
Note that at these extreme altitudes your brakes will get very hot in the thin air!
I bring my laptop with map software, it helps me plan my stops and plan alternate routes. Update it with current construction info before you leave. Check state DOT websites for travel info.
Example:
http://www.commuterlink.utah.gov/construction.htm Then of course
http://www.speedtrap.org. And for your phones: Trapster and Wardrive.
Bring lots of water, and drink more of it through the higher country of Utah and
Colorado.
Bring a digital camera - it might be a handy record in case of an incident. And bring binnoculars.
Buy or borrow some books on CD - these make the
trip go fast. Perhaps an autobiography read by an author, like Jack Welch's Straight from the Gut - whatever you think of him, I found it fascinating to listen to him read his book/his history and his time at GE.
If I could get away for this trip I would do it just for the drive in my NSX.
