A quick search of this forum suggests that the "good old days" were over more than a decade ago....

Anyhow, my recent stay at ParkSFO went as follows: arrived early (4:30-ish AM) on a Wednesday morning (non-holiday week) for a 6:00 AM domestic flight. Luckily, I found a self-park spot fairly quickly (even bypassing a few open but "less desirable" spots for a spot on Level 3 close to Level 2). My total stay was for 6 days (or more exactly, 5 days and 20 hours+, charged as 6 days as stated on ParkSFO website). On my return very early the following Tuesday morning, the structure was not overcrowded either.

I paid at a machine using a 3-free-day coupon. Here is the math: 6 days x $17.95/day = $107.70. Less 3 days free = -$53.85. Plus tax, $16.16. Total, $70.01.

Tax/fees shown as: CTAX 8%, AFEE 5%, FSUR 2%. So, total taxes/fees = 15%. Charged on the whole 6 days = $16.16.

(Presumably, CTAX means city and/or county tax. AFEE, airport fees? FSUR, some kind of surcharge?)

By comparison, I believe the SFO Long-Term Parking current charges are $25/day, with tax/fees included. I don't know of any coupons for that. So, I paid (after coupon) less than half that per day at ParkSFO. A decent deal, but that's in part because of the length of the stay. The max coupon at ParkSFO (that I know of) is 3 days off of 6 or more, so I was optimizing the discount (vs. 1 day off 3, or 2 days off 5, etc.).

https://www.parksfo.com/coupons/