Will be flying into Oakland on a Sat. What is the best way to get to downtown S.F., BART or taxi? What is approx. cost on both? Thanks for any help.

I'd take BART - check out www.bart.gov for schedules and fares.

BART would be my recommendation. It's really easy. A taxi would be a little faster since you're arriving on a Saturday, but it will probably cost around $40. A BART ticket is $2 for the Air Bart bus that actually takes you to the train, then another $3.50 or so for the train itself.

It depends how much luggage you have and how many are traveling. NO question BART is cheapest, however, you must board a shuttle bus at the airport to get to BART, then dismount and change to the elevated track. THEN, you arrive to San Francisco way underground and there are no porters to assist you. While not dangerous, dragging several bags through that dank tunnel is hardly the first impression you want to have of the city.

Supershuttle might be a nice compromise. NOt as expensive as a Taxi, and not as incovenient as BART for lots of luggage. It is door to door.
If you only have a small carry on and don't mind getting on and getting off things, then take BART.

I agree that traveling with a lot of luggage would make BART less convenient; however, the underground stations are not exactly "dark tunnels". If you have traveled on the Underground, NYC subway etc. you know what to expect.

If you have a hotel booked, you might ask them about shuttle services. Our helped us for return (back to SFO, but still...)