More Time to Play? Then Play!
Even with just a little extra time, you can start getting off the Interstates and traveling some of the 'other' roads of America that let you (force you, actually) to see the countryside at a bit closer range and slower speed. Remember that there was a vast, interconnected, inter-state system of highways before the Interstates were built, the 'US' highways (actually state maintained roads with a national numbering system.) They're still out there, often running parallel to the Interstates. I-80 follows much the same routes as US-6, US-20, US-30 and US-50 in various parts of the country, so you can at almost any time, get off I-80 and use whichever of those highways is closest. Some of them, US-6 across Pennsylvania and US-50 through Nevada, are quite scenic and a definite alternative to the superslabs. Others, such as US-30 in Nebraska, follow even older routes such as the old Oregon Trail and are strewn with landmarks and historic sites. In Wyoming, I-80 and US-30 are co-located, i.e. they are exactly the same road. But still there are side trips and great Old West towns such as Cheyenne and Laramie, or a detour down to the Flaming Gorge - Uintas Scenic Byway in Utah.
The thing is that as long as you keep an eye on the clock (or even the calendar) you can wander off the main road as often as you like, knowing that it will always be there, relatively close at hand, should you need to cover some miles or make up a little time.
AZBuck