OMG, without a doubt go to Rocking Z!
Welcome | Rocking Z Guest Ranch | Maria Anderson
I went there for a week last May and had the best time! It's family run/owned and everything is included for the price (room, food, ranch activities). I paid $200/night which isn't bad at all for everything being included. The meals are homemade and eaten family style in the main "lodge" and all the guests can meet each other and share their stories. There are a lot of international people that go there so it was cool to meet folks from other countries that shared the love of horses and the big sky country! I made friends with 2 sisters that came from England and we did all our ranch activities together because we were the same riding level.
They run the ranch around their horses and you can do as much or as little as you want. I did 2 trail rides a day (some long, some short), learned how to rope cattle, helped sort cattle, tried barrel racing, got to take the herd in and out (AM & PM), learned bareback, and even slept under the stars on a camping trip. It was magical! You won't regret it. I can't wait to go back!