Chengdu, Guilin and Xian

Well, here is my suggestion. You can spend 4 days in CD, 3 days in Guilin, and another 4 days in Xian.
CD:
Day 1: hotel check in; Chunxi Road; Divine Light Temple; Jinli Street
Day 2: Bronze Goat Taoist Temple; Jinsha Site Museum;
Day 3: Yangtze River cruise
Day 4: Mount. Qingcheng
Guilin:
Day 1: Li River Cruise
Day 2: Elephant Trunk Hill; Folded Brocade Hill;
Day 3: Seven Star Park; Reed Flute Cave
Xian:
Day 1: Bell Tower; Drum Tower; Big Wild Goose Pagoda; Going to Mount. Hua in the evening
Day 2: Mount. Huashan
Day 3: The Museum of Qin Terracotta Warriors and Horses

Thanks Carol for your excellent suggestions. Are there 1 day cruises ?The only ones I see are 4 day to 8 day. Where do I get the 1 day cruises ? Are the tours in Cd, Guilin and Xian readily available and what is the usual local cost ? Thanks for your help.

Sorry, I made a mistake. There is no one day cruise for Yangtze River. The shortest is two day cruise, and it starts from Chongqing City.
So if you really want to have one, you may change your CD plan to Chongqing, or you will just have not more than two days in CD, that's a little bit hurried.
For 4 days Chongqing plan, here is my suggestion:
Day 1: hotel check-in; Ci Qi Kou; Chongqing Zoo
Day 2: Dazu Rock Carvings; General Joseph W. Stilwell Museum
Day 3 & 4: Yangtze River Cruise
You can ask the hotel you booked in CD city to help you get a two day tour.
The tours in these three cities are available, don’t worry. The cost depends on your accommodation and transportation, etc. It would probably cost CNY2500 for 4 days in Chongqing, and CNY1500 for 3 days in Guilin and Xian respectively.

Or you can spend one to two days in CD to see the pandas and local distinctive streets. Then head for Chongqing by bullet train to explore that city and experience the Yangtze River Cruise, which usually takes 3-4 days for the best view.