My dad taught both me and my sister to drive (stick!) by taking us to a mall parking lot either before the stores opened at 10, or after they closed at 6. (Yes kids, malls used to close at 6, back in the day.)
Alternatively, pick any large random company down the peninsula, and their parking lot is not going to be very full on the weekends. Try taking a Sunday drive down to the Foster City/Redwood Shores area, say, 101 to Marine Pkwy, then loop around Bridge Pkwy.
My memory is hazy on this, but aren't there a ton of parking lots on Treasure Island, used for flea markets? Obviously you'd have to pick a day when there wasn't an event happening. And of course that merge back onto 80 is always a thrill.