Maybe there's not much where I'm going.
You're taking a trip across the entire country, how could there not be much there?

Your trip will take you by a million different things, from historic sites, to state and national parks, to roadside oddities - and that will be true no matter which way you go.

Having said that, if it were me, I think I would stay on I-70 through Kansas, and into Colorado and Utah. This route will take you right through the heart of the Rockies and along what is arguably the most scenic stretches of interstate in the country. It would also take you within a quick detour of several national parks that would all have amazing photo opportunities.