If you are not particular on your dates, there is a group that gets good rates that anyone is welcome to. Google Don White. This is the latest email blast I have recieved. I have not done this yet, but have friends that have gone numerous times. When it is not summer, the dates are usually on a Fri night.
Wisconsin Dells Kalahari Dates: Free water park passes with room always. No resort fees when staying in my block.
Friday & Saturday April 29, 30. Friday night from $109, Saturday night from $139 (deadline March 29)
Friday and Saturday May 13, 14. Friday night from $109, Saturday night from $139 (deadline April 13)
Friday May 27. From $109 (deadline April 27)
Sunday June 5. From $109 (Entertainment suites available $549
Sunday June 12. From $109
Sunday, Monday and Tuesday June 19-21. From $109 (Entertainment suites available $899

Sunday, June 26. From $129.
Saturday nights are generally only available at these rates when you also stay Friday night, are subject to availability and sell out faster than Friday nights. Saturday nights are not likely to be available after the one month deadline before each event. To make reservations for Saturday nights, you must call into reservations (1-877-525-2427)