If you like cockroaches, a plugged toilet, loud people talking in the next room, then I highly recommend the Tamalpais Motel.
My toilet was clogged when I checked in. I called the manager and they asked me to come pick up the plunger so I could fix it myself! I pressed them for better service and a couple of people showed up to unclog the toilet. They did succeed, but only after splashing toilet water on my bathmat, which they never replaced.
On the upside, when I awoke in the middle of the night to go to the bathroom, I only saw one cockroach on my bed.
Their prices have doubled in the last six months from 60 to 120 per night. They do not have a senior discount, but they readily discount seniors.
Overall, this place is awful and it would likely be a service to Mill Valley if it went out of business. There are much better motel/hotels are available in the area for the same price. Look around and steer clear of this one.