One of the best times I've ever had at a park was when Great America did Last Blast some time ago. The park was open on the first weekend November and it felt like 11 people (employees included) in the world knew. It was pretty damn cold, there were walk-ons all day, and the season was capped off with a string of laps on Iron Wolf just as some sleet was starting to come down.
I was there for this too. The last day the park was open, it was dead as hell. I was able to ride Batman, Whizzer, Demon, Iron Wolf without getting off. The only time I got off was to switch seats. It was cold as hell too, but I had a great time.