Hey Dan, first off congratulations!
There's so many great places up there...it's hard to single out any.
However, if you travel up hwy 17 north of the Soo then take 101 east to Chapleau there's a really nice camp on Anjigami lake east of Hawk Junction right off hwy 101. They've got an amazing beach there http://www.duenorth.net/campanjigami/
If you continue along 101 to Chapleau you can make the long drive into Missinaibi Provincial Park. Very remote, and huge scenic lake with amazing fishing.
From there cut down 129 and follow the signs to Wakami Lake Provincial Park. Great little underutilised park with good pike and walleye fishing.
From there instead of continuing south along 129 you can head east on the Sultan (E.B. Eddy) logging road over to hwy 144. It's a massive shortcut, but beyond that you can access Ramsey Lake off the Sultan road. There's a rough, but very decent boat launch and there's lots of nice island campsites. Walleye fishing is very good.
You'll be there in September, so you might want to check out the rivers flowing into the north channel of huron and the Superior trib's off hwy 17. That's PRIME time for pink salmon. There are literally millions of them, and when they first enter the rivers they're still very silver and aggressive. They'll hit spoons and spinners like crazy....very easy fishing!
cheers, Mike