If you are looking to extend your trip beyond the wedding there is plenty of fun to be had in the Pony area.
Fly fish the beautiful Madison or Jefferson river. Explore the Tobacco Root Mountains from trailheads right above Pony!
Check out Yellowstone National Park about 100 miles from Pony.
Have a soak in Norris or Potosi hot springs.
Do some shopping in Bozeman.
The options are endless!