If the day you flight is in or near holiday, DO NOT TAKE TRAIN, it will be a large number of people taking train in those days. As I haven't got enough information and don't know which the city you leave is, i have no idea how long the trip would take. You can check China domestic flight in the site below http://english.ctrip.com/ The flight from Beijing to Shanghai takes about 2h. On the other hand, the fastest train from Beijjing to Shanghai takes about 10h. Of course you should go to Shanghai by plane.

english.ctrip.com

1. i think you'd better take you trip after China holiday if you want to go to Bejing, it's too hot at that time in Beijing. 2.if you want from Beijing to Shanghai，i think you'd better taking plane， Flight time + wait time<3 hours,but if you taking the train ,it's will cost you at least 10 hours. P.S Guilin is so beautiful,you would like there

十月份国庆节是高峰期，买飞机票很紧张的，如果你订好了行程，可以早点在网上定好来回的飞机票，现在在网上买机票也是非常方便的，比如：携程网，http://www.ctrip.com/，票价一般比直接在所属航空公司买要划算，不是打广告哦。仅供参考。包括酒店都可以在网上订好，祝你旅途愉快哦~~~