It's all airlines at DEN, not just NW or UA or whatever airline. Just as a contrary datapoint to the 'never fly UA' person upthread, 3 years ago I had a UA supervisor check me in after the 45 cutoff (due to traffic delay) and personally escort my bag to TSA checked-bag screening and me to the front of the screening line. On any given day, a NW or DL or CO or UA agent might do that for you, or not. I learned not to push the deadline.

NW-specific: NW has seriously improved their baggage handling at DEN. I used to trash them regularly for how long it took to get the first bags to appear on the carousel. Used to be 45 minutes for delivery all the time. My last 3 NW flights with checked bags into DEN, bags were coming out by the time I got the tram from Concourse C after a quick bathroom stop. That's impressive given the large distance and manual baggage handling at an airport not designed for manual baggage handling.

To bstreeter, I've missed flights entirely from accidents on I-70. If you're flying out of DEN after most of a day in Breck or elsewhere around Summit County, it's a total crapshoot whether or not you'll get down the hill in time. I've taken to staying at an airport hotel that I negotiated a discount with free park-n-fly the night before on most trips.

Agree with GBadger and uavking about using the CO Pres Club - I use it all the time, and it's either a quick train ride 1 stop after main TSA or an easy walk from the "secret" airbridge TSA. Only a few minutes to the C gates (2 stops on train). Unfortunately they can't assist with NW issues because it's not a jointly operated club, but your WC membership (or STE+ status on an international trip) gets you in - for now.

Hope that DL/NW works something out on a bilateral deal with CO for this club even after CO leaves ST, because DL closed their small concourse C club early this year, and NW never had a club here.