If your looking for a good walk Elm Creek Preserve. I have a feeling that it would be a little bit out of the area your looking for but it's worth it.
Islands of Peace in Fridley is a short walking trail but it's right on the river and pretty scenic.
Banfill Locke park area is a good walking trail as well nice and quite.
Coon Rapids Dam park is a good outing as well. On the weekend you can people watch. Also on the west side of the river you can really get away from people if you have a desire to.