Places I have to see us play before I die:
NoDak
Minny
Wisco
Northern Michigan
MTU
Denver
I won't comment on North Dakota...but I can certainly understand why it's at the top of your list. : - p
As for the rest...
Minnesota - Cool rink where they definitely take pride in their history. Gopher fans are notoriously uptight, but the murals around the rink are pretty awesome and do a really good explaining that Minnesota used to be good in hockey. My favorite story here (non-UND victory category) was about 15-20 years ago. Minnesota was playing Michigan Tech (who was really bad at the time) and the Gophers were putting up a bunch of goals, which of course meant hearing that God-awful Rouser where they spell their state's name towards the end. On the big screen, they have sort of a "sing-a-long" that includes spelling out the state's name. It got stuck on the Ns, and probably a 1/3 of the crowd just kept going with it: M-I-N-N-N-N-N...you get the point. It was hilarious. It's my understanding Campus Pizza is no longer, which is really unfortunate, as that was probably my favorite place near the rink, and they had just perfect college town pizza.
Wisconsin - More of a basketball rink than a hockey place, but a lot of fun. Badger fans are a lot of fun to party with, although they used to have some pretty tight alcohol restrictions, so plan ahead. It's really unfortunate you were unable to see a game at the Dane...that was probably my favorite road venue. My favorite Kohl story was from the 2006-2007 season. Wisconsin had just won the national title, and North Dakota was one of the first games of the season, and so the place was electric. We sat just off the student section in the corner next to the Count-dude who practiced numbers with the Badger faithful (when they would score a goal, he would hold up a sign something along the lines of "2...2 goals...ah, ah, ah...we want more!" I presume it was to help the Wisconsin fans better understand which numbers are greater than others). Anyway, we got a pretty good heckling from the Wisconsin student section, including a rather loud rendition of "Aaaaashoooooole." It was a lot of fun, and North Dakota won in OT. Afterwards, we hung out at various locations on State Street and had a real good time with Badger fans.
Northern Michigan - I have only been to one game, and it was a NMU-Michigan State matchup from about October 2004. Neat arena. The Wildcats won, so the locals were in a pretty festive mood. That being said, I really was only in town for about an hour before the game, during the game, and then about an hour after, as I was dating a girl from just south of Mackinaw City, and we caught the game as part of a road trip back to her home town. That being said, October in the UP is a great time to visit.
Michigan Tech - Go during Winter Carnival. There may not be a better group of fans (not including UND fans of course) to experience a hockey weekend than Tech fans during Winter Carnival.
Denver - Don't go. It's a stale environment with a boring hockey fan base. The only games worth going to are DU-UND games (where the crowd is literally split 50/50) or DU-CC games (based on the rivalry). If you want to see hockey in Denver, I would suggest seeing an Avalanche game. If you insist on getting the college hockey experience, travel a bit south and go to a CC or Air Force game. Air Force has a really cool arena, and an even better campus. CC is moving to a brand new on-campus rink that looks pretty cool. If you absolutely must see a DU game, I would suggest hitting up Post (if you like fried chicken) or Spanky's (burgers) either before or after the game. Again though, and I can't reiterate this enough, skip the Pios and go to an Avs game.
Just my two cents. ; - )