How was the weekend at the Penn's Landing marina? From when I've been down there, I don't think it offers much security from the land side (obviously none of them offer much security from the water side).
Were you there for the Flugtag event, or just a coincidence? It looks like fun, but I'm guessing the combination of the show, plus power boats plus alcohol can make for interesting sailing.
We had a very nice time. Our sailing skills have improved enough that the 24mph gusts were easily manageable, and our dog came with us (first time in 2 years) and was very calm. I did not know about the Flugtag until I ran into a bunch of powerboaters at our marina who were heading out to see it. We stayed away from the hundreds of boats that were anchored, and watched it with binoculars from across the river. The Penns Landing amphitheater had an audio/video feed, so we could hear what was going on as we watched through the binocs.
Penns Landing marina is a very neat location for a one night trip. The docks were a year old and very clean. You're really right near the heart of all the activity. Security was better than I expected. There was a keypunch gate that prevented unauthorized people from getting on the docks at all times. At 10pm the cops sweep people off the seawall and padlock a second gate that keeps everyone away (slip holders get a key to the padlock). The weekend dockmaster is a part time liveabord who was constantly out on the docks watching over things. All this adds up to very good security, at least on the day that I was there.
As for seasonal rental, I don't know their rates. Bathroom availability is a question mark. The manager told me on the phone that they have remotely located bathrooms and shower for guests, but they'll take you there on their golf cart. When my wife inquired with the weekend dockmaster about them, he told her that they were "employee only" bathrooms, and he'd "take you there if you really want to use them, but only from 9-5." When I returned to my marina, some of my neighbors said, "Oh we really hate him. He tells that to everyone - maybe he's the guy who has to clean them up." We used other bathrooms and didn't need showers for a one night stay.
They also have no gas, pumpout, or other services that I could see.
If I were considering it as a home base, the lack of free parking would be a turnoff for me. But if you live in the city and have good transit options, it might be a really neat place to keep your Flying Scot if their rates are competitive. Their lack of pumpout and gas would not be an issue for you.