You provide some good reasons to hold a konvention in Michigan. In addition, Michigan has 3 former state highpoints which folks could visit (Mt. Curwood, Government Peak, Summit Peak). I believe that is the most of any state.
Two questions to ask about Michigan; where would the banquet be held and who would be the host (ideally a local).
These questions should be asked about the other candidate states as well.
I believe that the Brombergs have volunteered to host a convention in WI but I haven't heard about banquet facilities near Timms.
North Dakota would be a very nice place for an "outdoor" convention.
Also, Dave Covill analyzed each state in an article in the recent newsletter.