Berkeley to the city is a mass transit breeze, in fact anywhere BART goes is convenient for travelers. It is fast and if it takes you to the far reaches of the bay area. The one of the few places it does not go is into the north bay where I live, they do have bus bridges that could make that work if you were so inclined. In the 60's Bart was proposed to go into Marin county which is in the northbay, it was voted down because it would attract the " wrong" type of resident. Guess what I ended up there anyway. If there was something Washington state could consider it is a system similar to BART it is astronomically expensive I cant remember the per-foot price but it is shocking