Q & A on US road trips

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Planning a very long drive trip (OH-AZ-NV-CA as main stops).

While the main intention is visiting some friends / relatives (long pending, thinking about for years), there are also some plans to stop at tourist spots / sites.

The drive from Columbus, OH to Flagstaff, AZ (grand canyon) has necessitated an overnight stay at Okalhoma City, OK about which I have absolutely no idea.

Also, I-70 / I-40 are quite new routes for me as I've never driven in these at all.

Those who have experience in these routes (i.e. St Louis to Oklahoma / Oklahoma to Flagstaff) can please alert for unusual things to look for! Will very much appreciate it!!
(Things like "no-gas-station-for-100-miles-as-the-area-is-Indian-reserve" kinds)...