not sure where you are coming from or which crossing you plan to use. if you use Sarnia/Port Huron Bluewater Bridge, there is a 24 hours super Walmart in fort graxoit (10 min from bridge). Detroit Metro Airport is about
1hr 15min from Sarnia.
If you're crossing the bridge from Windsor, there's a new Meijer at the Oakwood Blvd exit, there's also a Target too. Watch for the signs to Greenfield Village on I 94. After you get off the bridge you take I96 to I94.