I lived in Anchorage, AK which is larger than Helena and I lived close to my job and further away. When I was further away I lived on the hillside, essentially, in the mountains and it took me 30-45 minutes to get to work (not very bikable either) and from home I still had to drive somewhere to get to a trailhead for hiking/cycling, etc. I could also take my gear to work and do things on the way home which is not a bad option.
I also lived close to my jobs (5 min drive or 15-20 minute walk) and personally, I liked living closer to my job and in town. For me, having access to a hiking area, essentially a trailhead or a trail network is my dealbreaker. If you live in town you will likely have sidewalks in neighborhoods if nothing else, and in many western cities, it's likely you might have access to a trail network without driving. This is the key point IMHO. I currently live in the suburbs and we have pretty good sidwalks and within .5 miles is a trail that leads to an open area with lots of trails, so it's a good compromise.
Country living can be great but if you have to get in the car to even take a walk, which in many instances is the case in rural areas because the streets are narrow and walking on them does not feel particularly safe, then that is a big negative/deal killer for me. I have had the best of both worlds where you can walk out your door in the country and access great walking, hiking, skiing, etc without driving anywhere. Roads with very low traffic volumes, nearby trailheads/access or dead end streets offer this the best. But these spots almost inevitably require the longest commutes.
Unless you are a hardcore year round bike commuter, I'd think really hard about the possibility of bike commuting year round in Helena. Winters are long, windy, cold and dark in those parts. Much easier done on municipality cleared and lighted city streets than rural routes.
Take into account not just distance of your bike/walking commute but also topography. Hills can make many commutes difficult to impossible for amateur bike commuters.