Whitefish is a charming town. I hope you all enjoy it. The Flathead Valley (in which Whitefish sits) is gorgeous--but not exactly a shopping mecca.
There are no stamping/scrapping stores in Whitefish that I know of.
There is a Ben Franklin store at the small Whitefish Mall that I hear carries lots of crafting supplies. I assume it also carries some stamping stuff.
Your other two options are the town of Columbia Falls (about 15 miles away) or Kalispell (also about 15 miles away, in another direction).
All About Memories is in Columbia Falls on Hiway 40 West (phone 406-892-1999). I've never been there, but hear that it has a good selection (some have reported that the prices may be a little higher than they expected). Another I know nothing about is Grandma Betty's Scrapbook Store (406-892-5420).
In Kalispell there is Northland Hobbies on Hiway 2 West (phone 406-257-180
. It is an independently owned general hobby store, but has a good section for stamping and scrapping. They do carry some limited Nestabilities. (Edited: phone number for Northland Hobbies is not appearing correctly on-screen, even tho in my post it has no smiley-face. The number is 406-257-1808. )
There is also a Joann's in Kalispell, but IMO its stamping/scrapping section leaves a lot to be desired.
Finally, the stamp manufacturer Paper Inspirations is located in Kalispell. They have no retail outlet, no store, no place the public can go in and look or buy. But they told me you can order online and indicate that you would like to pick up you stamps in person instead of paying shipping (406-756-9677).
Hope this helps! Enjoy your trip! It is truely an area of breathtaking beauty.