If you are off to Yosemite that day, then I'd drive as far as Walnut Creek and be mostly out of the morning commute traffic. IIRC, there are a fair number of motels off 580 around there. Late at night, it should take less time than in the morning commute. And yes, getting to 580 from 80/580 is a pain when there isn't rush hour traffic. I speak as a frequent traveler there, former resident of Marin and hater of CA traffic. I'd also recommend getting a reservation at a hotel ahead of time if you are traveling on the weekend. I was traveling to Yosemite last month and the cheap rooms from Marin to Modesto were mostly sold out on a Saturday night.