We just got off the Panorama and used the off site parking. Here are my thoughts. First, I was expecting the absolute worst and we actually had a pretty good experience. We're Platinum so I had a 10:30 am check-in for embarkation. I arrived at the port at 8:30 am.
I drove up and dumped the luggage. They had porters waiting to receive it. They gave me a parking permit and instructions to the off site parking at the convention center. It's about a ten minute drive, located off Ocean if you know Long Beach. I placed the permit on the dash and the attendants saw it and directed me to the designated lot and a parking space. Then we jumped on the shuttle bus and they drove us back to the port. All in all it was a smooth operation and we were back to the port by 9:30 am or so.
Disembarkation was pretty easy as well. Again, being Platinum we were off the ship by 9 am. I checked the luggage the night before (getting too old to schlep it myself) and grabbed it in the terminal. Facial recognition makes clearing customs a breeze for us. We proceeded to the bus parking area and got in a short line. The driver loaded our luggage into the bus and drove us back to the off site parking. I tossed everything into the car and we were on our way before 10 am.
It's certainly not as easy as parking in the terminal and I don't think I'll be booking anymore cruises on the Panorama because of being forced to park offsite. However, it certainly wasn't as bad as I expected. The day we left the convention center parling lots were deserted. A week later when we returned they were packed with a considerable amount of traffic in the area so it depends on events taking place, though we were out of the lot fast so it's probably a non-consideration. They charged me $20 a day and it should show up on my shipboard account charges in the next couple of days. The terminal garage currently charges $23 per day.
So that's what we experienced on the June 8th cruise. I would recommend getting to the terminal early even if it means waiting a while to check in. Hope the info helps a bit.