John, great thread! Hadn't seen this before. Interesting choice of word - "best." You could have used "favorite," like I probably would LOL.
Okay, on those long stretches of I-5 between Sacto and LA I'd have to agree with your choice of the Allman Brothers, especially Brothers and Sisters. Or the Eagles. Mainly because I drove that span regularly in the 70s and 80s and I wore out those cassettes. Or Toy Caldwell (Marshall Tucker). Wet Willie or Elvin Bishop. Maybe Norton Buffalo. Definitely Roy Buchanan. Brubeck, Getz, Jimmy Smith and lots of CTI jazz - Grover, Eric Gale, Ron Carter. Straight ahead stuff for an uninspiring stretch of highway.
Now I rarely drive those long distances, sticking mainly to well known roads here in the NW. For Chuckanut I'd prefer Hendrix, especially Electric Ladyland. For the Cochahalla I like speed music, from Dixie Dregs to Bill Frisell to Fabulous T-Birds, especially at night. Here on The Island it could be just about anything...
Those are the Best. And don't ever 'been there, done that' to me again...
Hah.