If you would like a little more space and/or peace and quiet, you might consider staying in Island Park, which is about 5-10 miles from the ranch.  There are a number of lodges and/or hotels available, though please note that these are usually booked for the summer as early as January. 

We've been able to see a few of these places, but not all. Here are a couple of the options in Island Park:

(list to be added soon..!)

Another nearby option is one of the many campgrounds in and around Island Park.  There are several on the Henry’s Fork of the Snake River, and others that are quite scenic. Additionally, the weekend of the wedding is prime camping season.

Henry’s Lake State Park has 50 campsites available.  Reservations are recommended.  You can reserve online here: http://www.idahoparks.org/parks/henryslake.aspx.

The Caribou-Targhee National Forest administers a number of different campsites in the area.  The closest one to the ranch is (to be added?)  , though you can see other options available here:
http://www.forestcamping.com/dow/intermtn/targ.htm.  Again, reservations are recommended.

West Yellowstone has many places to stay, and it is only 28 miles down the road.

(list to be added soon..!)