Where's the Toilet? is an interesting site that reviews restrooms as if they were restaurants or hotels. Too bad they don't review them in my area.
Like the PSL Service Plaza, the bathrooms here are shaped like a U, with the sinks along the base and two rooms of urinals and stalls making up the legs of the letter. The men's room can accommodate about 30 people at a time, give or take. The women's room, judging from what my companion told me, can hold about half that.
It's a Teutonic place, with dark tiles covering the floor and bland gray tiles on the wall. White sinks, white urinals and white toilets, with black stall doors separating them.
I visited this plaza twice, both out of necessity. The first visit was in early afternoon, during which the place was overrun by tour buses and tourists, and as a result it was a horrible experience through and through. There were so many people there that the bathroom felt like a subway station at rush hour -- people pushing and shoving just to stand their ground and not lose their place in line. Kids were running around everywhere, jumping into and splashing around in the various liquids found on the floor and throwing towels and trash about.
I managed to score on a stall on this visit instead of a urinal and found it horrifically dirty -- the floor was covered in urine, mis-thrown toilet paper and bits of feces (no kidding). And the stall doors had a considerable amount of graffiti on them, including a very prominent hand-written advertisement for third-party presidential candidate Ron Paul. I didn't think the endorsement was very flattering, but I guess it does show where Paul's influence can be felt.