There isn't much left of the old Route 66 (which my grandparents traveled with me a lot when I was a kid). The Interstate highways cover a good part of the old route. The parts that are left often go through sleepy little towns - or ghost towns - that died when the highways went througn and/or bypassed them. The are still things to see besides Oatman (and the route through there isn't doable in anything larger than a class B) if you're willing to make side trips and spend time... but it ain't what it used to be.
Rob