Oshkosh is the home of the Experimental Aircraft Association AirVenture Museum which is a great museum dediated to aviation. They don't just display airplanes there, they rebuild them and fly them. More information can be found here.
The EAA has a big air show in the summer and one day I might go, but for now it seems a bit hot and crowded for my tastes. An off season trip to the museum makes a great day trip, so we did that instead. (There were seven of us in three airplanes.)
Our departure from Rochester, Minnesota was delayed by a low but thin overcast. It was one of those days where you need an instrument rating to pop through the clouds to get on top and get going. Without an instrument rating we had to wait for the clouds to start breaking up. We were able to get out using 'special VFR' and finding a hole in the clouds to use to get on top. (The trend was gradual clearing of the clouds - in an emergency there would have been enough holes to get back down safely.) On the way over we were plagued by haze. It was flyable, but visibility was less than the normal CAVU (ceiling and visibility unlimited) that I like.
I will leave the pictures of the museum aircraft to the museum web site - they do a better job of it. These pictures will give you an idea of what to expect if you go.