Typically see a lot of games played at US Cellular Arena in CR. They can do this because there is no team playing at US Cellular. Hilton would be to big, and why would you send a game between Waukee/Valley, Hoover/Urbandale or Ankeny/SE Polk to Ames. This doesn't make sense from a travel standpoint, and throw in the fact they can't even fill the lower ring at Wells Fargo, Hilton would look empty. The other problem you run into is the Big 10 and Big 12 are not done with the regular season, so they are still playing games next week. The Knapp Center would make the most sense in DSM from a size standpoint, but parking is terrible.
Biggest issue - the boys union sets their dates before the Big 10/Big 12 ever set there conference schedules, so it's difficult to plan locations like Carver/Hilton when they don't know when they'll be playing. Other issue is weather, what happens if the games were postponed and the next night you have the college team hosting a game, then you are scrambling to find a location.
Let them play at the high schools, as long as it's a neutral location. You can't be the atmosphere with a bunch of people packed into a high school gym.