The annual EAA (Experimental Aircraft Association) AirVenture takes place in Oshkosh each year. This year, it will be held from July 23-29. It is an impressive event and one to consider if you have a bit of extra time to spend!
If you are into cars, you may want to consider attending the Iola car show from July 12th-14th. Just be sure to book your rooms early as it is a major event in the area.
A trip to Wisconsin is not complete without a visit to the legendary Lambeau Field! You can take a stadium tour and then enjoy brats and cheese curds for lunch or dinner. :)