There is an additional large hotel close within the Fairlane Town Center development.
Adoba Hotel Dearborn (Formerly the Hyatt)
(313) 592-3622
600 Town Center Dr
Dearborn, MI 48126
http://adobadearborn.com
You can certainly park your car in the garage (which is owned by Ford) with the other cars and walk or grab a ride from The Henry to the Adoba. While it's not as nice as The Henry, they do have plenty of rooms and it's only $125 for our dates.
Alternatively, Ford owns the Dearborn Inn (Marriott operates), which is a very nice hotel right next to the Product Development Center. They only have outdoor parking.
The Dearborn Inn
20301 Oakwood
Dearborn, MI 48124
(313) 271-2700
http://www.marriott.com/hotels/travel/dtwdi-the-dearborn-inn-a-marriott-hotel/
Rooms at the Dearborn Inn are currently $229 for our dates, and it is about 3 miles away.