Jamawani thank you very much for your wise input. It saddens me, but I suppose you're 100% correct in saying pick the route or the time of year.
Unfortunately I have no experience choosing my own route and it terrifies me. I certainly strayed from my maps a few times on the Southern Tier, but on one occasion I ended up on a busy two lane road with no shoulder and cars honking at me for 10 miles. That was a nightmare.
I suppose one alternative if I stick with ACA maps would be to head south on the Pacific Coast route from San Fran down to LA and then cut in East on the Route 66 route. From there it'd be a short ride to intersect with the Grand Canyon Connector (I've always wanted to see the Grand Canyon). From here I could grab the Western Express Route and head North West to Lake Tahoe. This would be a much shorter trip, but should all be doable this time of year. The other thought is maybe flying to Key West or Virginia and starting from there. Back to the drawing board