The Frontier! One of the mainstay restaurant/bars in this area, the Frontier is the place to go if you want a true Montana dining and bar experience. Set back in the small town of Rexford, the Frontier has some of the best Steaks and Fried Chicken I've ever had. Wooden decor, outdoor patio, good for families. Drinks are cheap, food is pretty reasonable too, and the service is ok. Just be warned that they cant be pretty snobby to out of towners, especially if you look like it! But it's a good place to get some eats and hang out with some taxidermied animals. One of my favorite places to get some grub in this area.
Beware though, the women's bathroom doesn't have a door, so it's a real "outhouse" kind of experience!