Lots of big open wheat country in western OK, then some cotton and corn on east side of the TX Panhandle.  Around Amarillo you get back to very wide open flat wheat country all the way over to New Mexico, then it changes to mesa lands with only ranching.  If you make it this far west, run down to the Palo Duro Canyon.  Good place for a picknic or camping overnight if it isn't too cold.