Duluth is beautiful! Lucky you! I've only been there twice, even though it's just a few hours away from me
I love running around lakes. Running in the woods is okay, so long as it's during the bright day. Otherwise I get scared!
My ex is a mountain biker so I'd go running on the mt bike trails when he would bike. Those are FUN. Logs to jump over, quick turns, dodging trees, I HIGHLY recommend finding some near you