Kinda depends which way you are going on I-5. I don't recommend 128 to 29 because of the tight curves. It is doable though.
If you take 37 to Vallejo, you can pick up 780 to 680 to 580 to 5. Or, you can go E. on I-80 from Vallejo to Susuin City and take 12 east to 5. That way adds about 10 mi. back north, but avoids all of the urban traffic.
If it were me, I would drive 101 to Petaluma, take lakeville highway to 37, then to I-80. (The exit in Petaluma says Vallejo on the sign)If going south, I would go west to 780 (1-2 mi) and E. to Benicia and take the bridge across, which becomes I-680, and take it to Dublin and pick up 580 and follow it to I-5.