We had an awesome experience staying in Detroit at the airport!!!
We drove there and actually used the same "Big Blue Deck" that another poster mentioned. The only thing was that we drove around for about a half hour in the lot looking for something, but it was ok because we got there the day before!
I checked on Expedia and found lots of really "cheap" airport hotels but we actually decided to "splurge" for the nite and got a rate of $99 CAD through Expedia.ca for the Westin right in the airport!
Let me tell you, this is one of the nicest hotels that we ever stayed at... it was right in the airport, so the car stayed at the airport and we took shuttles all over.
The Westin Heavenly beds

were awesome but DH will always remember it as the time that we couldn't sleep all night in the most amazing hotel room ever because we were too excited to go to WDW.

We even saw Cedric the Entertainer (comedian) in the lobby staying at the same hotel! Oh yeah, and if you have kids, they'll love that most of the rooms overlooked the runway... we had a great window view, and completely soundproof. DH loved it too!!!
However, if you do go with this hotel, I recommend bringing some food with you because we found the restaurants too expensive, we ended up ordering in delivery pizza.
