The key here is timing, and the biggest warbird air show within the span of time you have mentioned, is the Commemorative Air Force's "Airsho". The promotions haven't yet begun for the show, but it is scheduled for October 12-13, at the Midland Intl. Airport in Texas. I know of a couple of guys in the UK that are regular Duxford goers, who also tend to travel to Texas, most years, to catch the CAF's Airsho.
I believe the average attendance is probably about 50-75 warbirds (both CAF owned and others), and the majority of them are going to be flying at some point during the show. Included will be the world's only airworthy B-29, B-24A, possibly two or three B-17's, up to 5 B-25's, 5-6 Mustangs (including the rare C-model "Tuskegee Airmen"), numerous Navy fighters and bombers (including the world's only airworthy Helldiver, and one of only three airworthy SBD's), the Tora, Tora, Tora replica Japanese aircraft, possibly a P-63 and P-39, possibly a Spitfire and a genuine Zero, and more. Everything of course changes a bit, year by year.
Another well known warbird show that takes place during that time period you might plan to be in the U.S., is Wings Over Houston, which actually usually takes place just a week or so after the CAF's Airsho.
The other shows I tend to consider the most, all take place in earlier months of the year, like Geneseo, MAAM's WWII Weekend, Military Aviation Museum's Warbirds Over the Beach (their new airworthy Mosquito will be the star of the event this year), Thunder Over Michigan, Planes of Fame Air Museum's annual air show (P-38's being the big theme this year - they're hoping to have 5-6 examples there, flying), etc.