The other folks have done a great job explaining Miles City. Let me offer a few other items of interest. Not sure if you are looking to buy, rent, or build, but housing is difficult in Miles City, especially if you plan to rent. Rentals, at least good ones, are few and far between. The housing market itself right now seems to be pretty decent and there's lots of options.
There's lots for kids, especially the age of yours, to do here. Miles City offers a lot in the way of sports, but also other activities. We have a great art center that offers art classes, 4-H is a big deal here, as well as a very active Girl Scouts program and a couple different dance groups.
We are located two hours from Billings, the largest city in Montana, so pretty much anything you can't get in MC, isn't that far away.
As someone else mentioned, fishing and hunting is a big deal here. You won't find much for bass or trout fishing in this part of the state, except in some of the smaller stocked ponds, but the rivers and some of the larger reservoirs like Fort Peck offer a wide variety of other fishing opportunities. There's several large parcels of public land here not far from town, as well at FWP's Block Management program which opens up a ton of private land for public access.