<human>: Can you give me the gist of the text in a nutshell?

So I've convinced the Boyfriend that he needs to see more of the country and the three of us (my little dog too!) are driving instead of flying to Tennessee from Seattle soon (end of July). We will be taking the I-90 and I-70 route and are already planning on stopping off at Yellow Stone WY and hopefully Badlands in SD. I've driven other Highways across the states but not this one. We sadly don't have much time for exploring and I was curious if any locals might have some thoughts on must see spots as we pass though. Less of a city/town person, more of a wilderness/natural wonders type person. The less fuss and cash involved the better! Even if it's just a really nice lookout spot or a sweet waterfall I'd love to know where its hidden! 

Also, cheap but not shady - *Vacancy* horror movie come true - motels or even B&B's would be very useful too. Sleeping in the car isn't really comfy and it can get pricey quick not including the huge pet fees for my well behaved 9lb Dachshund...
And if this thread works out, I will be asking again (especially since I'll likely be by myself) for the drive back as I want to take a different route and see even **more** sights :)
<bot>: Driving from Seattle WA through ID, MT, SD and such on I-90 & I-70 to TN, what not known stops should I try to see?