Clipper is not as slick as Oyster, although I have not found anything that is slick as Oyster and I've got 8 different RFID transit cards.

My suggestion would be, as someone who visits SF once/twice year to someone who I assume is only visiting for a short time:

* Just buy a BART paper ticket from the BART vending machine at the SFO BART station.

* Then buy a Clipper card at a downtown BART station, or wherever you can. (Or maybe you could you buy it online ahead of time and have it shipped to where you are staying/working?)

* Just put 'cash' on it, especially if you are only there for a short time. Do not worry about passes, ride books, or high value tickets.

* Do not use autoload, or plan on using autoload, while you are there. Also, do not add value online. It takes days to setup autoload or for value to be added if you do it online, so only add value at a station. (I've had Clipper and Translink for several years and I have gotten caught or been confused since the online services are far from instantaneous.) Walgreen's might be instantaneous, but I have not tried it yet.

As a visitor, I have never had a card not work with my cash value, except when my original TransLink card became damaged somehow and just quit completely. I think the new cards are better designed since that chip is no longer exposed.

BillJ