I commute in Minneapolis also. I use platforms with Five Ten shoes.

The shoes finally wore out though after 6 years of use, so I replaced them with the now discontinued Teva Pinner 2 shoes. If you can find the size a pair of the Teva Links are coated in a waterproof material for these shoulder seasons of ours. Personally I think a nice wool sock will cover the shoulder seasons.

During winter I use a set of winter boots with the same platforms.
Columbia Men's Snowblade Slip Waterproof Boot Cold Weather Boot, Black/Charcoal, 10.5 M US | Amazon.com
These are the boots I went with, I wanted something that I could easily slip on when leaving in the morning and slip off when I got to my office. As for wearing out boots, it depends. I used for a very short time a nice pair of duck style boots for my commute and I noticed the bottom did start to get a little beat up from daily use from the platform pins.

Lastly you could find a used set of Lake boots and not put the cleats in, those would work fine for the winter months, or line your shoes with plastic bags/bread bags if you want to go on the cheap.