http://www.peninsulatrailcoalition.com/index.htm
This is a great, mostly flat trail. It was an old railroad grade. There are however two very short and steep hills on either side of a creek that runs through the trail. I just walk them, it only takes two minutes.
There is also great road riding all over in the Port Townsend area. Check out these great maps as well.
http://www.ptbikes.org/maps/index.html