Your ideas are very sensible, as always.

There are some issues, tho. Larkspur is very unhappy with being the terminus. That's one of the reasons the end of SMART at Larkspur will be on the north side of Sir Francis Drake, about a quarter of a mile from the ferries. The Marin City extension would assuage Larkspur, bring passengers close to the ferry terminal and would make it possible to replace the northern half of Golden Gate's trunk #80-101 bus line with light rail, and grab most of its subsidy. One point I do share with Diggs is that GGT should run SMART or whatever is in its place.

Another big advantage of electric light rail is that it can handle gradients ruled out for freight rail. For example the lift bridge over the Petaluma River south of Petaluma could be replaced with a fixed high bridge because streetcars could easily handle the ramps. And a very desirable viaduct over 2nd, 3rd, and 4th Streets in San Rafael would be feasible. Many in the Northbay, including yours truly, favor loco-hauled over dmu's, but San Rafael is strongly opposed because it feels that would invariably lead to long trains that would block the intersections of these major, very congested streets.