If you're going from Traverse City to the bridge and obviously you'll want to avoid US31 north of Petoskey, then take M72 from Acme (just east of TC) over toward Kalkaska. From Kalkaska you can take US131 northward about 18 miles or so to a tiny town called Alba. Turn right onto Alba Road (C-42) at the only 4 corners and head east. This road will take you right into Gaylord (and I-75). The bridge is only about a hour north.
C-42 is a nice road with some curves, but I used to live in Gaylord and we took this route very often when heading over the Traverse City. Gaylord will have plenty of places to stop & shop for your travel needs. If you need fuel, stop at the Meijer store right along M-32 west of town. They will have diesel & it will be cheaper there than further north.
Of course you can follow US31 north through Charlevoix and Petoskey to Alanson & the detour. Be warned though, Charlevoix and Petoskey are busy in the summer and traffic slows often. There's a draw bridge in downtown Charlevoix and can back up traffic and downtown Petoskey is quite busy in the summer with traffic backups often.
