After 3, next day free is with paid admittance and does not include the 2 for 1 pass price...
and to answer acapps08 question, No there are no "deal" on passes after the park opens for the season.. in fact the price goes up a little bit and stays there all year... not sure what "regular" price will be this year. it appears the price is now 82.00 and can be split into 2 payments..
you can find current pricing and benefits on their website..
Good luck, and have fun!