I haven't been to one in several years, but the monthly shows in Detroit were usually not very good. They consisted primary of WC animals and CB corn snakes (and their clan). Some of the the dealers had animals in deplorable conditions (e.g. several dozen baby iguana in a 20gal long aquarium).
You might have some luck with arachnids as there were usually a good selection of tarantula. I would be hesitant to make the trip expecting to find blue tongues. If you did, they'd likely be WC parasite-infested junk.
In contrast, the annual(?) Michigan Herp Society usually has a great show. But I don't know when the next one is since I live in Texas now.
Jeff