Yangtze River Cruise is a must. There are many sights along the river. Some included in your cruise, others are optional extras. It depends which cruise you pick and which sights you are interested in.
Be mindful, many of the sights along the river are reconstructions of the originals; once the damn was constructed, it resulted in all villages along the river banks to be completely covered by water. Many historical landmarks were dissembled, then reconstructed on higher ground. So they are not in their original locations.
We must admit, we didn’t really do a lot of research into the sights of the cities, both Chongqing and Yichang seem to either be arrival or departure points for most tourists on the cruise.