Funny, my DV home is 1.5 miles from the St. Regis. There are concerts on the ski run at the DV Snow Park Resort on Saturday Nights in the summer. May be worth investigating what and if there is a concert on the 26th of August.
Just checked the Park City Entertainment guides, nothing as far as outdoor or Park City events on the rally weekend.
Park City is a great place. 140 restaurants in the city. No place I can think of that one would park a GT in the town. St. Regis has a nice funicular railroad down to Deer Valley Resort for town access. Keep the GT parked indoors at the hotel. Uber is the best way for transportation into Park City which is about 2 miles west. Main street has all kinds of SUVs parked everywhere. Probably GT unfriendly for an evening out. Utah just passed a 0.05 alcohol driving limit. 1st in the nation, but probably doesn't go into effect until Jan 1, 2018. Just FYI.
One other point of interest. It is frequent, in the Wasatch Mountains in August, to have almost daily rain storms, usually somewhere around 2-5 PM, as the clouds build up west of the Wasatch and then a 2 hr rain storm in the Park City area. So, just as FYI, it happens especially when the day looks clear.
A great photo shot would be at the Montage Resort in Empire Canyon at the top of the Deer Valley Resort, with the entire entrance and exit access roads of the hotel parked with Ford GTs. A great mountain vista.
Any Park City area questions, leave me a post.