Local repeaters are set up for different purposes. Sometimes range is deliberately limited to avoid conflicts between repeaters. Some are set up to extend the range of hand held or mobile transceivers over a mountain or ridge. So it would be wise to check for the area you are going to. I cannot tell whether your assumptions are valid for Colorado but generally you made a good point.
Here in Germany we can find repeater maps in the internet (printable and some as Google Maps). I printed one on a A5 sheet and laminated it. That does not claim much space and is helpful if I forget to remember to program the frequencies or fail to reach the expected repeaters.