Practically every exit in the state has a 'Lucky Lils' mini casino...it is very simple, a big chain of casinos, all over Montana, and they do not care how many you visit and do this. Walk in and sign up for the players club, they advertise it everywhere, no big secret. They give you $5 for joining to gamble with... go play a dollar and get your free drink, then cash out. Proceed to the next Lucky Lils in town or area or next town. With two people you get $9 guaranteed at each stop, or $10. With more people in the car, each of you sign up and pool together for the gas cash and voila. Seriously just got done doing this, no hassles, they even look you up in their system and do not care whatsoever that you joined 10 times earlier that day in different nearby towns.
Also there are other casinos just like this, actually ran by the same people I am sure...if you see a 'Suds N' Fun' or 'Montana Lils' they are the same exact deal, hit 'em up. Oh and I think 'Dotty's' does it also, but that's a different less apparent chain.
When you're not hustling, check out Missoula. The coolest little town, and probably the one stop other than Yellowstone you want to make. Culture and drinking here. The bars do not care if you walk out on the street with their draft beer in glass, and even walk into a new bar with the other bars brew. The people are very laid back and very drunkenly fun. There is a couchsurfing ranch there, http://www.orangeacresmontana.blogspot.com have not visited personally but heard good things.
A must stop is 'The Oxford'...a historic bar downtown that serves amazing breakfast for the hangover.
