Originally Posted by half pint

I'll be driving into San Francisco (Nob Hill) getting there mid to late afternoon on a Thursday. I won't need the car until about 06.30 on the Sunday morning.
My thoughts are as follows :
Park the car at a BART airport car park and then pay $6 a day parking ($18) then pick it up on Saturday evening and park it overnight in the Sutter Stockton garage at a cost of $8 . Retrieve it at 06.30am and leave SF.
Are there any potential problems with this strategy ? Am I being stupid paying out the $18 for the Bart parking?
Any help appreciated (supplied in the most basic of ways)
Thanks