This was my first full in 2016, when the race was still in August.
If you are adequately prepared to do an Ironman, my experience is that elevation of 5400' will not be a problem. That said, I did go a week early (from Indiana) and hiked up to 13,600'+ to make sure I would be acclimated by race day. I noticed the elevation past 11,000', but not much below that. I did a couple easy runs and rides, and was fortunate enough to be able to swim a bit leading up to the race as well.
Generally, the event was well-produced, lots of great communication from the RD leading up to, during, and after the race, and a stunning location. My wife came along for the race, and my parents flew in for a few days too. Lots of breweries around, and tons of hiking from beginner level all the way to advanced.
Something that hasn't been mentioned yet is that this is a "high desert" environment, meaning the humidity is low, and the sun is more intense. Pay close attention to your hydration and be sure to plan for this kind of environment.
I found the run to be the most difficult, somewhat due to the nature of the Boulder Creek Path. At one end, there is a "swimming hole" for lack of a better term, and it was crowded with people who had no clue that a race was going on, and didn't care to stay clear of the path. At mile 20 of the marathon, I had completely run out of f*cks to give, and bowled through a couple people, so be prepared.
Other than that, a great venue, great organization, and a fun race. Enjoy! I want to come back and do Boulder again soon.
Brenden Macy
Sports & Entertainment Attorney
I am Drive. I am Grit. I am Determination.