The Mo' is probably Michigans best Spey river, the only problem with it is that the H2O temp gets pretty high in the summer. The dam is top draw and not bottom.
The Big Manistee is next best followed by the St. Mary's (borders Michigans UP and Canada). There are a couple of other UP streams where one can use a long stick. Further south in Michigan is the St. Joe, big water but pretty urbanized. Too many dams and people.
Wisconsin is also blessed with some big rod waters. As is New York and Ontario.
We have lots of smaller streams where a small spey may come in handy; but were you to cast the whole head you would be in the trees.
Most people fish the Pere Marquette, a small over fished gem of a river that gets way too much use and abuse. Some use a spey rod there with a float (indicator) or chuck and duck.