there's plenty of river to ride along if the bike path is what you're looking for, on either side of the river. i know on the moline river front there are multiple park areas along the way which you may choose to stop and play a little or not. i can think of one major one in davenport on the ia side i think its centennial park, but that path also runs the river for as many miles as you wish to follow.
there is a path along duck creek that runs along a major creek on the ia side, through davenport and bettendorf. pretty centrally located in the city, depending on where you are staying. also plenty long to get in some good miles with the fam. a few parks along that route also.
there's alway sylvan island on the il side that has a variety of single and double track that you could play on with a nice grassy area for the kids to play in while you take a short singletrack spin. about 4 miles if you can follow the main loop.(it's not really well marked and takes a local to navigate correctly, but there are tons of trails to work with wound through the island)
hope that gives you a little to work with. post up if you can when you get in town and surely someone will be glad to show you around.
the wheels on my bike go round and round......