Drop the Yangtze Cruise idea like a hot potato, immediately. Overpriced and eats up a lot of time that rapidly becomes repetitive and boring. Most of the cruise takes place on the Chongqing-Yichang segment anyway, not the lower Yangtze between Shanghai and Wuhan.
Guilin (Yangshuo area) is a possibility, but you need to be aware that the time frame for your trip (late spring/summer) may come with rain in that region. Sometimes a LOT of rain. Wouldn't be my choice for month of June.
Suggest for scenic part you consider alternative of Jiuzhaigou/Huanglong in upper Sichuan province which can now be accessed by air rather than the long bus trip. Where have your parents already been or not been?