You are really trying to hump a lot of road in 6 weeks even if hustling to OK! Once in OK, go to amarillo in tx, and go north towards colo on 87/287, pretty much nothing but miles and miles of miles, but there is Palo Duro canyon you can visit just so of amarillo, plus in amarillo there is the texan steak house, the cadilac cemetery (just to west). Once in colo you cn go to Pueblo then up I 25 to colo springs (lotsa tourist stuff, manitoo springs, garden of gods, the af academy, up to denver into wyo. Wyoming has the best info centers anywhere, have water, sewer dumps etc. keep north to casper then 20/26 to the west this will put you on track to tetons and yellowstone. To return from this area 189/191 from Jackson to rock springs and then find route home at your leisure as you can continue south to some of the other NP/NM's in north colo and utah.