Suggest making it earlier in the year and going to the northeast. After all, this is the place to be for the trees changing color ... just ask the thousands of "leafers" who come just for the colors.
And the Canadians would feel like they were going to the beach!
Speaking of beach, how about late August, early September at Rehoboth beach in Southern Delaware? It's got a great boardwalk, hotels and bars ... all within walking distance once you are there.
There is Ocean City MD's Delmarva Bike Week too... it's awesome. We could take over a hotel and make a stand against all the Hardley's. I'm going to be there no matter what, been going for the last 3 years and have a blast every time. September 15th - 18th this year, could show up earlier or stay later as a special group. Hotels are really cheap just before or after as a rule and reasonable even during. This place is one long ocean side drag (street) with every price range and type of hotel/motel you can imagine.
For the gamblers out there, another idea would be Atlantic City NJ. It's like Vegas without the stifling heat.