For a different take on local life take a San Diego Red Trolley - not the retro heritage look-alike version on rubber tyres - but the real electrically-powered thing.  The Blue line trolleys link Downtown San Diego with the international border at San Ysidro for Tijuana.  Mix with the locals going about their business for just a few dollars: even a Day Pass that covers all three Trolley lines only costs $5 for a day, from the self-service ticket machines at each trolley stop.