Pretty much all the hotels near the airport offer a park-and-fly rate and a hotel shuttle. It's always more than the cheapest nightly rate. I always call around until I get the cheapest because it's never consistent. I've always done this the opposite way - spending the night before at the hotel - so don't know about doing it spending the last night. Sometimes a limo can be just as cheap too, depending on how long you're staying. Should you go with a lot, ParkSFO is a bargain for covered parking and if you do a search for them they frequently offer a one-day free coupon online that you can print out.