I'm looking for places to take Cub Scouts fishing this Summer. The size of the group could be anywhere from 4 to 30 kids/parents. We are based in the Wayne Westland area. Any recommendations within a 30 or so minute drive would be nice.

Kent lake near Milford is an excellent spot for that.  Lots of beach and shore real estate, boat launches, boat rentals, and even a bonus waterpark.  Mostly largemouth and panfish Look up Kensington metropark if you aren't familiar.  Ford Lake and Belleville lake both have parks that you could fish from shore on (Ypsi and Belleville) Walleye, bass, and pike.  That's pretty much what comes to mind, I actually live on the west side, just spend an inordinate amount of time over there.

Yeah, I was going to say Kensington Metropark or Island Lake.  If Heavner Canoe rental is still there, that's fun to fish and paddle.  Though you might not want kids fishing from canoes...

We took our Pack to Spring Valley Trout Farm in Dexter. A bit of a drive, but they guarantee that each kid will catch a nice fish, they'll fillet them there, and they have facilities to have a picnic. You can grill them right on the spot. We went on that one day this April when it snowed (kinda miserable, not gonna lie), but it was still fun.

Their rates for Scout groups was pretty good too. I don't remember the exact cost per kid, but it was very reasonable. Here's their website: http://www.springvalleytroutfarm.com/