CKG is close to Three Gorges, so that would be a natural thing to see/do. There are several day cruises departing from Chongqing of varying quality, with cheaper prices on those not targeted to foreigners.

Your interests strongly suggest Shanghai, perhaps instead of Beijing. How about a side trip to see a canal town?

Many foreign tourists head to the Great Wall, pandas, and the Terra Cotta warriors. These would appeal to kids.