The worst time I've ever had was at PGA last year.
They had two people working at the entrance, and they were acting extremely rude. Vortex was running one train, and opened only as we were leaving. Delerium was closed, so was the swinging ship, and about five other flats. The rapids and log flume were down, and it was a hot day. The place was packed too. Top Gun was only running the red train, and had the the first two rows roped off, and had a two hour wait, so we didn't ride.
Invertigo was testing, but never opened. Demon was also closed. Grizzly was running one train, which got stuck on the anti-rollbacks on the second hill, so they had to push the train up about five feet so it had the momentum to roll. It was closed when we left.
Drop Zone was running about half of its cars and had its overflow queue filled up. Psycho Mouse was the only coaster running more than one train/car. It was also the only coaster that didn't take five minutes to dispatch (Well, Top Gun took about four, but that's still slow!)
We left after ninety minutes, and didn't ride a single ride.