Finally, get involved in whatever the kids are interested in.  You may plan for this to be a mostly-fishing trip but if the kids aren't into it as much as you thought for whatever reason, don't force it.  If they want to swim, go out and swim with them.  Catching crawdads, frogs, or weird bugs?  Give it a shot!  Let your son see your inner child and you'll be amazed at how much you will bond on your trip.

Oh yeah, should be blueberry season, too.  Find a big ol' berry patch and let 'em loose with an empty ziploc if they are berry lovers.  Once they get a taste of fresh wild blueberry pancakes you may be lucky to even get a bite yourself.