I did a day trip PMD-SFO a couple months ago because I had an e-cert that required certain fare codes and PMD-SFO was the only reasonably priced fare out of SoCal to SFO. It indeed has free parking right across from the terminal, which probably offset the cost of fuel driving from SNA to PMD.
The whole atmosphere reminded me of the pre-JetBlue days at LGB. It was very empty and very relaxed. My flight was nearly full, but even that didn't overwhelm the single agent at UX that handled check-in and boarding, nor the couple of TSA agents at security. There were a couple more agents that handled ground ops for the aircraft, for a total of maybe 10 people that work at the airport altogether. The CRJ had a real quick turn - arrived, deplaned, loaded baggage, boarded and off we go. Since PMD has USAF operations, the runway is some 12,000+ feet long. We took less than half the runway to become airborne.
My return was the last flight of the night, which arrived after 10pm. The Flyer bus was already there waiting, but I didn't take advantage of it because I didn't find out about it beforehand. The whole experience was very pleasant and relaxed, a complete change from all the hassle at LAX, and even SNA to some extent. I just with I had some more time to look at the aircraft museum and their outdoor display near the entrance to the terminal.