Keep in mind they bought Northwest Airlines a few years back. So, they also use Minneapolis and Detroit as hubs.
Based on my experience I would recommend going through SLC vs Denver at least in the summer. My flight back from DEN to BOS was delayed because of afternoon thunderstorms(wind shear). Apparently, this is a common occurrence in the summer at the Denver airport as the storms roll in off the front range.
Interesting to know. Told you I hadn’t flown in a long time.