Sounds like you're doing a lot of travelling, so I'll try to give you some info on the highways around the area as well.

gsspatoulas said:
Yea I am interested in the following cities:

Grand Rapids: Excellent coverage in city, small pockets of no coverage south along 131.

Holland: Excellent coverage in city, nearby highways good, no coverage along 40.

Traverse City: Roaming agreement, can't say what the quality of coverage would be like. (If you have a NW plan you won't be charged though).

Saginaw: Great coverage in city, good coverage along I75, no coverage south down 13

Indiana:
Fort Wayne: Good coverage in city (some dead spots, good coverage with some dead spots along I69, intermittent coverage at small townships along 30.

Ohio
along route 23 to Columbus: Columbus is great, 23 is covered by a roaming agreement with AT&T, so I can't say what the road will be like.
GSS

Hope that helps!!!