Also the parts of Millbrae that rival Park Slope in cost are not walkable to the subway (well technically walkable but quite a walk) vs the places I was looking

Also the parts of Millbrae that rival Park Slope in cost are not walkable to the subway (well technically walkable but quite a walk) vs the places I was looking at were a 5-10 min walk to the subway station. Trains in NYC come much more often, later, and frankly Millbrae is no Park Slope ;)