I wouldn't describe Rock Island as anything other than a shiitehole.
I've never been to the Quad Cities, except for being driven through them once as a kid on a family roadtrip. Excited to see all the tourist attractions there: John Deere HQ, the Colonel Davenport House (in Rock Island, not Davenport), the Vander Veer Botanical Garden, the Fryxell Geology Museum (if Augustana University is open in Sep), and that Lincoln statue located in front of a railroad bridge whose construction was allowed by a lawsuit where Lincoln represented the railroad company against entrenched ferry interests, etc.
Can't find anything to do in Bettendorf, though I will surely enter it just to I can say I've been to all 4 quad cities.