On my two week trip out west (from Indiana), I was able to visit Colorado (Denver, Colorado Springs area), S. Dakota (Badlands, Black Hills area), Montana (Drove through Montana, staying one night in Billings, then going up to Glacier), and drove all through Wyoming (Stopped off in Cheyenne for lunch, stopped in Gillette for lunch after visiting Devil's Tower, drove through the entire state from Grand Teton to Denver).
I will say this, every state is governed by humans, and as such, your freedoms are only what the local elected "leaders" say they are at any given time. I would bet that every state "out west" has some sort of "law" that allows the governor or various town managers/mayors, to invoke some sort of martial law. I was absolutely shocked that Montana has a statewide smoking ban. For a state that one thinks is heavy on individual freedom and choice, it was pretty clear Montana is still nothing more than a Democracy ran by the majority. Just because the majority is pro-gun doesn't necessarily mean they are pro-individual freedom.
While the entire area is nice, the one issue I have is that of heat during winter and medical care.
All the areas I visited can get brutally cold in the winter. Plus, they can get a lot of snow. Everyone figures that answer to this issue is stocking enough food and having a wood stove. Wood stoves eat wood, especially when used as the only heating source. While these areas are rural, there are still people in the area. If something happened on a nationwide scale, and you could get propane or heating fuel for your home, you would definitely need a source of good hardwood to be able to survive the winter months. The thing is, there is a lot of what appears to be pine type trees, which aren't good for burning (from what I hear). So buying land with a good source of hardwoods is a must. But remember, if things go to hell, not only will you need to take watch to protect your home, you will need to take watch to protect your wood, and your lot for sure. In this aspect, if one has the funds and knowledge, Wyoming makes sense because of the wind. Get a basic electric heater, or baseboard heaters, and put up some solar and smaller scale windmills on your property. Of course these may have ice issues, so you would still need a good amount of wood as a back-up. If you can get the wood issue taken care of (I would say a very large barn, filled with enough wood to last at least two winters, you would be good to go...that would likely be enough time to allow this country to "reset" in the urban areas, then normalcy would resume), then you would be OK.
From what I can find there are no Level 1 trauma centers at all in Idaho, Montana, N. Dakota, S. Dakota, or Wyoming. Close level 1 trauma centers are in Ft. Collins, CO. and Salt Lake City, UT.
With that being said, here are my thoughts:
Mid-sized metro areas I visited:
-Billings: Not too bad of a town. Large enough to provide decent shopping, places to eat. Had an industrial feel in some aspects. I have heard about a "smell," but didn't smell anything when I was there.
-Rapid City: I really like Rapid City. The entire area seems pretty nice. Spearfish is a smaller town about 40 mins or so away on the interstate.
-Cheyenne: Cheyenne was just a small scale city. I read there isn't that much there. I like the area around the Sam's Club and Wendy's, looked a little new than the other sections of town (this was on the north end).
-Kalispell: Similar in size to Cheyenne and Rapid City, but a very nice area in the mountains.
All the above cities are decent places. Rapid City and Billings (metro areas) are the larger of the four.
Some other mid-sized cities in this area are:
-Ft. Collins, CO. This is about 50 miles south of Cheyenne. In fact, there are people that want to live in Wyoming, but commute to Ft. Collins for work. Ft. Collins is similar in size to Billings, MT.
If one needed a larger population center, I would avoid Denver. Denver is too much like other older, larger American cities, with a decent enough sized lower-income population to cause problems if things collapse. Colorado Springs seemed nice, at least the areas where we drove around. There is a military presence in Colorado Springs, which could be good in some ways, bad in others.
Three other larger metro areas are the greater Boise, ID area, the Salt Lake City, UT area, and the Spokane, Wash. area. Never been to any of these places, but the info available on-line makes them appear to be decent places.
Note: All of the above areas are experiencing decent growth. One thing that really sticks out is that for most people, in order to relocate, one likely has money and/or a stable job lined up. I visited the area in 2007, and housing was crazy back then, thought not as crazy as other parts of the country. Anything near the Grand Tetons or Yellowstone was nuts: $1M for some properties. A few months back I looked at properties in Whitefish and Columbia Falls, MT. Housing prices have dropped, significantly. Newer, log cabin type places still are somewhat pricy, but there are older homes that can be had for decent prices.