Flight
Among the travel options listed below, the cheapest method of transportation is driving. Gas at its most expensive is ~$2.50/gal as of March 9th, 2020. Assuming 20 gallons per mile over 1600 miles, the trip is $200 one way. At the time of writing this, the coronavirus has decreased flight prices and so it is possible to find a cheaper flight, but that will not last. Regardless of where you are coming from, there is going to be some tourist attraction along the way that would be interesting to see. Although for some it would be quite the distance, there are many sights to make it worth while. Hotels are all beyond walking distance, and I am not too sure about the Uber/Lyft/Taxi business in the area, so you will likely have to rent a car anyway.
Flight
This is the one and only airport in Kalispell. It is a medium traffic airport, as Glacier National Park is world-renowned, but still flights are not cheap. It is an estimated 35 minutes from the wedding venue, with equal or less travel time to any lodging.
Flight
This airport is the next closest to the venue with an estimated two-hour drive to the Flathead valley and Kalispell. Missoula is a beautiful town and is home of the University of Montana, where Sam and Brittany met. Plenty of lodging is available in Missoula as well, and it is feasible to plan your initial few nights in Missoula and drive up to the venue/new lodging on the 23rd. The drive is lovely, and if you are stuck behind a truck moving too slow (looking at you Bill) you can enjoy some gorgeous views. While in Missoula, check out the wide assortment of local breweries (Big Sky, Highlander, Kettlehouse, etc.), hike the M and the L, and rent some tubes from the university and float the river!
Flight
Spokane Airport is located in Eastern Washington and is an estimated four-hour drive (five with a time change) from the venue. It is not as tourist friendly as the other airport cities, but it is the highest traffic airport of the three and also is the only airport to fly southwest, so the flights may be cheaper. The views on the drive are incredibly beautiful, and you will drive through Lookout Pass where you may even see some snow in July (off the road of course). You will drive through Plains, Montana where Brittany spent part of her childhood and they sell ammo at the local gas station.
Rental Car
The standard rental car companies are stationed in all of these airports. Take your pick!
Hotel
This Best Western is central to everything you may want to do. Just South is the Flathead Lake for swimming and the Mundhenke Family home. Just North is the town of Kalispell for basic needs (beverages, groceries, etc.) and is the biggest city before Glacier National Park. It is also one of the closest hotels to the venue with an estimated drive time of 13 minutes.
Hotel
Another option that is in town in Kalispell if you are wanting to stick to being in town and closer to more options of restaurants and activities.
Hotel
This Hotel is directly next to the mall and main street of downtown Kalispell. Great if you want to be based in Kalipsell with some shopping options.
House Or Rental
Among the wide variety of hotels, there are also many houses/rooms that are rented out during the summer so you can find a nice ranch guest house or cabin as your lodging.