Iron,
If all you want to do is get from point "A" to point "B" you can do it in that amount of time (Denver to Yellowstone).
I did that trip 3 yrs ago with my brother-in-law - slow down and injoy the sights, if you take the same route we did there's a lot of nice riding, all kinds of switch backs, lots of fun if you stay within your abilities.
I did the trip on a rented Electra Glide and was wishing I was on my America the whole time!!

Good Luck

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