Has anyone used the Bart connection from the airport to downtown San Francisco? According to Sept. National Geographic Magazine this is now possible. Would this get you near Union Square where we will be staying? Also have you had experience with the shuttle running to the Hilton in this area? How near and how convenient?

This topic has been discussed in detail a couple times recently. You might try poking into the archives.

Yes, the BART will take you from SFO to downtown SF - check out www.bart.gov for schedules and routes.

Thanks so much for the website to the Bart. We could get the super shuttle-make reservations,but not sure what time our arrival will be as we are driving from San Luis Obispo and dropping off rental at the airport where we picked up the car as we got off the plane.

You don't need a shuttle reservation coming to the city. You need a reservation only going back so you don't miss your plane. There are plenty of shuttles at the airport, like taxis.