Oshkosh
Entrance queues are very rarely longer than 15 mins with about a dozen people 'taking your money' at each booth.
The warbird park is brilliant with lines of 40 Harvards, a dozen or more Mustangs etc the norm.
The first thing we saw in 2007 was a bright yellow RV on amphibious floats.
Don't expect an airshow quite like the UK ones - there will be big gaps and lots of aerobatics and no published itinerary as far as I can tell. However you will see lots of planes you've never even heard of.
Take a good pair of walking shoes you'll need them! They do get the occasional rain shower/thunderstorm but it's usually very warm. Make the most of the trams and definitely take the bus for a dollar to the seaplane base. (Worth an afternoon in itself). You'll never see it all so make plans to go back next year.
Have a nice trip.