Turnkey,
Here's my 2 cents. I've always had good luck with Hi Tec boots (
www.hi-tec.com) The critical part about any boot, regardless of the brand, is the fit. I think you're right about NOT needing waterproof boots because your feet will tend to get hot and clammy. Breathability was always important to me and if your boots should get wet to the point that they soak through to the sock, carry an extra pair(socks) with you.
I think that Academy and Sports Authority both carry this brand. And I believe that you'll like the price also.
Remember to try on several different styles and brands to see what fits best for you and DW. Hope this helps and I know that you'll enjoy your trip to Colorado. And there's no better way to see our wild America than on foot.