Re: Great Lakes Steelhead/Salmon
For the mid-western part of the lower peninsula of Michigan, salmon will be showing up soon, probably peaking in numbers during the first two weeks of October. Steelhead will also be present during this time, since they often follow the salmon to feed on eggs. It's tougher to target steelhead when there are so many salmon in the river. If the goal is steelhead, I'd suggest early November, once most of the salmon are gone.
You won't have trouble finding rivers to fish, or points of access to the rivers on the western Michigan side of things. If you have the flexibility to be mobile, you might be able to better target the best fishing since the specific timing varies a bit from specific river to specific river. Throw in other variables such as weather, it helps to be as flexible as possible.
Hope that helps a bit.