From the comments section:

At the end of this month (the 29th), I’m flying to Denver (evening arrival) with the plan to get a rental car and drive to Colorado Springs (in order to attend the Society of Actuaries Spring Meeting May 30-31, if anyone cares). Yes, there is a reason I’m not flying directly to Colorado Springs… That follows below.
On Saturday (June 1), I’ll be driving from Colorado Springs to Steamboat Springs (via Denver, from the maps) to spend the next week with my parents, niece and nephew (who are themselves flying into Denver from Cincinnati and driving their own rental to Steamboat Springs on Saturday)… They arrive around mid-day, so I was planning to leave CS no earlier than the afternoon so as not to beat them to the place we’re staying (as it’s their reservations, not mine).
Then the next Wednesday, I’m planning to head back to Denver to fly back here to New Hampshire, on a noon-ish flight.
So, am I going to run into any of this scary traffic at the times I’m looking at being on the interstates (D to CS Wednesday evening, CS to SS via D Saturday afternoon, SS to D Wed to arrive noonish)? How long should each of these take, if you don’t mind me asking?
(Also, any suggestions of things we would just “have to do” while in the area are welcome…)

Alright, Colorado People, answers in the comments, or email Jack from the linked comments section.

Make sure you take E-470 (the tollway) from DIA down to I-25 on the way down to the Springs. Vastly less traffic than 222/25, and it gets you around all the I-25 freeway construction. It will cost you about $4.50 in tolls, but (a) well worth the cost, and (b) it's a business trip, right?

I wouldn't expect much traffic on I-25 southbound to the Springs on Wednesday evening if it's after 6 except on the northern end of things (down to Castle Rock).

Figuring you want to get to DIA a couple of hours ahead of the flight on Wednesday, you still shouldn't hit too much traffic -- though it always seems a bit congested on I-70 east between 25 and 225. Once you're down on the flats, out of the mountains, I would guess 30-odd minutes to DIA.

Thanks for that! Very practical info. And yes, it's business travel so tollways are a great alternative.

Now I'm in the same place as the itinerary... I'll be arriving around 5:11, so with allowances for time to get lugage and the car, won't be on the road South until after 6.

You'll probably still hit a bit of traffic once you get to I-25, but nothing like what you would non-tollway.