The Bighorn 50k is an incredibly scenic trail race in Wyoming that has been run since 1993. The 2025 dates are June 20-21. Registration opens 1/5/25. In 2024 there were 125 finishers. The closest airport is Sheridan (SHR) with Billings, MT (BIL) being a distant second. United Airlines flys into SHR and is a direct transfer partner with chase. In terms of hotels that can be paid with points IHG has Fairfield Inn & Suites and Marriott Bonvoy has Candlewood Suites. Both of those programs are chase transfer partners making these easy to book with points.
The Bighorn races are only a four hour drive from Yellowstone and 5:30 to Grand Teton so this could be the perfect race to tag some national parks afterwards!