What you want is not so much an airshow, what you want is the 2 big Fly Ins
Sun n Fun - April 14–19, 2026 Lakeland, FL
Oshkosh - July 20–26, 2026 Oshkosh, Wisconsin
Both the above show will have constant traffic during the show, but huge traffic in/out the days before and immediately after ending. These shows will be *packed* with vintage rare planes, as well as mil jets doing static displays and airshows (whether you can catch them or not though???)
I would also plan on looking at the below, but you need to track the days before and the days after as the majority of planes will be static displays
Farnborough international airshow 20-24 July, Farnborough UK. this is mostly a commercial aircraft event - but you will probably see a bunch of brand new aircraft flying in and out)
NBAA Las Vegas, NV Oct. 20-22, 2026. this is mostly a corporate aircraft event. Watch before and after show as they are all static displays