Hi, and again, thanks for all the helpful comments! The trip is shaping up to look like this:
Staying two nights at the Chippewa Hotel on Mackinac Island, then moving in to the Grand Hotel for the last night (the day of my birthday!) I found a special rate for the Grand on-line, still not "cheap" by any means, but a whole lot less $$ than what I was first quoted. So I am excited to have the oppty to check it out for at least the one night!

Then, we are planning to stop in Frankenmuth on the way back home, and I have booked a room at the Bavarian Inn Lodge, and hope to try the chicken dinner at the Bavarian Inn rest, and go to Bronners, as well as see some of the German themed stuff they have in the town.
I am really happy to be able to go to Mackinac Island (a dream coming true for me!) and again, thanks to all for your help.