hummmmm, trying to think back to all the trips I have made, there are 2 that spring to mind.
Alton Towers(Sunday 2nd April 2000) It was the opening weekend of the season, so was expecting big queues, but totally got the opposite, I think it had something to do with a big thunderstorm 1 hr before opening, so it probably put people off. When me and my friend got there, we were stunned, the park was nearly deserted, there was just hardly anyone around, All rides were a walk on excect for Hex which was new and had a 30-40 min queue, We even went on Nemesis anfd Oblivion about 5 times each and not once did we queue up for any of those rides, Great Day
DisneyLand Paris(November 2000) Was expecting it to be empty because it was winter, but I didnt expect the park to be absolutly deserted nearly. Only spent 6 hrs 30 mins at the park, but squeezed in 7 rides on Space Mountain, 7 rides on Indy,4 rides on Big Thunder,2 Rides on Pirates of the Caribean, and every other major ride once or twice, longest queue of the day was Space Mountain at 15 mins once, it even became a walk on at times even though its the most popular ride at the park, and I stayed on twice in a row on the coaster.