Last Summer we used GoodSam Trip Planner for a loop from Orlando to Yellowstone; to Yosemite; to Kings Canyon; to Tucson; to El Paso and back to Orlando. Seven weeks. Almost seven thousand TV miles.
I tweaked each day's route to use the roads I wanted and then downloaded each leg to my Rand McNally RV7710. (Batch download..all legs in one pass.)
I had to change some as we went along, (Add a side trip to Bodie. Delete crossing Death Valley. etc.) but the basic info was there whenever I needed it.