I'll probably take 128 up to Calistoga since those roads are pretty safe. Especially since it might be dark when I get there.
The I-80 route looks interesting; I usually can't find roads that connect Alta to Blue Canyon when I ride up there, but I saw a PG&E recently that might be paved. If that road works out, it would be like 3 miles on the highway, which isn't too bad. I'll definitely look into it-- I had no idea that I-80 was bike legal on that section.
Thanks for the tips!