I've lived in Denver and used to go out to Atlanta one week out of every month for a short time, so I'll take a stab at this;
I agree that it's like comparing apples to oranges, so it's difficult in comparing the two.
As far as similarities, I'd have to say that the airports are based on the same model.
Airports; DIA has Concourses A, B, and C. ATL has 5 or 6 concourses and counting, with a train to connect them. DIA is a joke. Literally. But it serves the city pretty well. Other than the fact that it's way out in Strasburg. It's like north and WAY east of the city. Atlanta's airport is at the south end of the city and they have this train system that starts there and goes all the way up to the north end and maybe beyond by now. At some point I think it splits off a bit. On one fork you can go to the Medical Center section. Now, in the middle of the MARTA system or at the center of the city, you can go east and west. I haven't gone that way before. But at the center, you've got that Underground place. I haven't heard about it post-911. Is it still there? If not, that's a bummer. Advantage, the ATL.
Traffic; Denver doesn't have the best roadways in the world, but TREX did spruce it up pretty nicely. If E-470 ever connects all the way to C-470 at Golden or wherever and becomes a "Freeway", then advantage Denver. That Spaghetti Junction with the 75, 85, 400 Interconnector and whatever it's all called-just is a mess! That and the fact that every roadway in Atlanta is called Peachtree! All that being said, I changed my mind. MARTA vs. Lightrail, advantage again, the ATL.
Sprawl; The fact that the ATL is right out in the middle of nowhere, they've got Denver beat hands down when it comes to sprawl. But then again, look at Waterton Canyon (Deer Creek Canyon, whatever you call that road), 285, Morrison Rd, 6, 70, etc. on any given Monday morning. I see no evidence that the Rocky Mountains are stopping sprawl to the west of Denver and that is disgusting. Advantage again, the ATL.
Sports; The Rat beat Reeves and thus validated Elway's career. Advantage, Denver!
Industry; Coke vs. Coors. Can't really compare those on any level!
They both are equally usless to me, so tie. Krystals vs. Good Times, DENVER!!!!!!!!!!!!!! Krystals give me the urge to regurge. Krispy Kreme, Denver owes the ATL a thanks here. Thanks for NOTHING! Advantage, ATL.
(that one's a tie)
Overall liveability; drier air and 4 seasons give Denver the nod. Don't think that the ATL is a picnic when it gets down to 20! That Brown Cloud in Denver is temporary and usually blows away into Nebraska along the South Platte valley with a good brisk wind.
Denver has drinkable water. I'm not sure about water in the ATL. Advantage, Denver.
Night Life; Gold Club vs. Shotgun Willies. Gee, I don't know. Ask Terell Davis. LoDo. Broncos. Rockies. Avs. Nuggets. A thriving downtown and growing city, I'm gonna go advantage Denver.
Hospitality; As far as hospitality goes, I get along with all different types of people, so it doesn't matter where I'm at. I get hospitality everywhere I go. Advantage, neither. Not an issue for me.
Outdoors; Don't think that the ATL isn't near mountains and rolling hills. Up towards Gwennett (sp??) County, I saw some places where you could probably hunt, fish, and who knows what all. They have an abundance of trees, plants, greenery. Denver's climate is altogether different. Not necessarily worse, just different. Denver is at the gateway of World class mountains, skiing, mountain biking, rock climbing, river-rafting (granted, you've got to drive down to my river-the Arkansas or West Water), etc. Advantage Denver.
So I've gotta say the ATL overall. But if I HAD to live in one or the other, I'd pick Denver.