We visit Poulsbo a couple of times a year. (
We were just there) It's a nice destination. Kim likes to visit the shops and wander the downtown area. There's not enough testosterone in that for me so I usually work on boat projects. There are a couple nice restaurants and the bakery is great.
Beyond that, I don't know of any "must do" activities. I understand the
Naval Undersea Museum is nice. It's a short way away at Keyport, but we've never been there.
For me, Poulsbo is just a nice place to relax.