Thanks for the replies especially JieJie's very detailed one!
We have no problem dropping Shanghai from the itinerary but I do wish we could still see Suzhou and the surrounding areas. We'll just have to plan that into a future trip! My oldest son was really looking forward to the gardens there. Are there similar gardens in any of the other areas we are visiting?
We also are wondering if a day and a half will be enough for the things we were hoping to do in Xian. Of course, we are planning on seeing the warriors. We also wanted to see the pagodas, the towers, explore the Muslim quarter and the kids thought biking the city wall looked like fun. Would it make a difference if we left Chengdu on an earlier train to get into Xian earlier? I don't want to cut into our time in Chengdu either but all we really had planned for there was seeing the pandas and the Leshan Buddha. Is there something else there that we should make time for? I also am aware I don't know the ins and outs of the trains so maybe taking an earlier train is not advisable?
I'm sure I will have more questions as I deal with the specifics of the travel within each city. Thanks again for the help already given!