In Petersburg, you'll want a 7 or 8 wt. rod and you'll mostly be targeting chums and pink or salmon. You'll mostly be using a floating line, but either having a short sink tip or attachable sinking leaders (poly leaders) will be goods. Check out our Chum and Pink Selection to get an idea of the flies to use. Chum & Pink Selection
The other thing you'll want to consider is the trout and dolly fishing. In the creeks, they will be keying in on eggs and in the lakes they'll be eating leeches and buggers pretty good. For the stream fishing, a 5 or 6 weight rod will do just fine with a floating line. In the lakes, a sink tip will help greatly. Check out the Southeast Bead Selections and for the lake the Lakes of Alaska Fly Selection.
Best of Luck!