I went to the park the past three nights (29th, 30th, and 31st) and the crowds were the lowest on Monday, and were slightly busier each night. That stated, the park was still very, very slow on Halloween - with walk-ons for every ride except Firehawk. Each maze had a maximum of 10-15 people in line throughout the evening. The bare bones nights were awesome, and if they are around next year I would highly recommend going. They will likely even be slower next year - with everyone required to have a purchased admission.