For an easygoing trip near the house I recommend running from the Cedar Rapids Roller Damn to Highway 30 (past Highway 30) on the Cedar River! I do this trip at least 3 times a year, it takes roughly 5 hours! The water is quiet and you will run into an occasional fisherman or another group of canoers or kayakers! The scenery is nice! There are a few privately owned cabins along the way and plenty of sandbars to get out and stretch on or swim.
Old river road by the shack tavern is where we put in and we fallow that raod south all the way across highway 30 to old school (stay left and go through the gates its okay!) road where we get out at a crick bed about a city block past 30.