This one I got a cheap entry for and wasn't big on my schedule, but was a pretty uplifting event and started December off right! This one took place entirely within Denver's City Park, with benefits and limitations in tow.
Pros: Decent parking if you get there early, very festive race-day expo, post-run christmas cookies, lots of good vibes
Cons: the course had a lot of ice and the park statutes forbid sand or salt (caution was needed), a large number of "green" or non-runners clogging the path (two abreast at most pls!), a little awkward if one is not of Christian faith, too much Mariah Carey holiday refrains (you know which one...)
That said, I PR'd despite the ice patches, and I saw at least one rabbi costume, which was greeted with jovial inclusion. Everyone was clearly having a great time, myself included!

This one was the inaugural run, so not a lot to work with: low attendance, basic course, no real expo or swag at packet pickup or the event itself. All the earmarks of a training run you get a medal for.
That said, a lot of heart in this one. The event staff really wanted this to be a good run, and although the course was just some paved trails through semi-rural small town Colorado, it was pretty charming still. The course itself was flat and fast, and decent aid along the way. I PR'd by nearly 10 minutes!
For finishing, I got a boring but comfy shirt and a basic but shiny medal. This fully exemplifies the event itself: a shiny, basic, boring but comfy event. On the surface it's just another medal, but it's got a soft spot for the efforts readily apparent.

I've done a few of these in different places (did the inaugural Japan Warrior Dash), but this was the most fun!
The obstacles were by the numbers, with the exception of a snow pack, which was a hell of an August surprise! The problem was that most of the "warriors" in my heat were first timers, and as such were having their own personal "I can DO this!!!" moments and slowing the more serious challengers down. A lot. I probably lost nearly five minutes just waiting for these people to get over it, literally and figuratively.
That said, level of challenge and challenger aside, it was a beautiful course, and had a few awesome surprises along the way. The event was perfectly managed, parking was a snap, plenty of free swag from vendors, good food and drink, and the most easy-going friendly party atmosphere yet! The Portland Warrior Dash I did some five years earlier felt like a muddy version of Burning Man, and the Japan 'Dash was like a disjointed mountain road race with pensive cosplayers, but this one in Colorado was just... Fun!
If I do this one again, I will register for the party and atmosphere, and not fuss over my finish time. I'll save that for s more serious course. This was just a goofy fun time to be had by all!

So, do you like mountains, running downhill for hours and smaller-scale events? This is the one for you!
There's a 1,500ft elevation drop over the full marathon course, and you definitely feel it when you finish. A finish that's waaaay faster than you normally would, I might add. You run along the Rio Grande trail, starting in Aspen and finishing at Basalt (nope, hadn't heard of that town either). The views are spectacular: once in a lifetime views that most will never see, and that alone has made this run worth it.
The event itself is rather small, maybe less than 500 full marathon runners, and maybe half that for the half. This is probably why the expo was so small. My perspective is that if there's less than 5 vendors, then mail off the packets: don't make them mandatory pickup the day before (especially in a remote mountain town that's hard to reach!).
That aside, the finish line was well organised, decent refreshments and music, and clear instructions and support. Water stations along the course were well spaced and well manned, street crossings were painless and fully supervised by volunteers, and transportation was quick and painless.
If/when you stay in Aspen for this event, strongest recommendation is the St. Moritz Lodge. Cheapest prices in town, but great walking distance to the starting gate, great amenities and it's not a faceless Super8 style hotel. Feels like a nice BnB, somehow.