Between Beijing and Chengdu

If I only want to make one or two stops on the way from Beijing to Chengdu, where are the best places? Smaller towns and/or some hiking would be nice.

I know that Xi'an is on everyone's must-see list, but if I don't really want to do a bunch of sightseeing and see the terra cotta warriors, should I still go? Is it a terrible shame to miss it? I've been to most of the other big cities, but if someone can convince me, i'm game.

In order of preference: Jiuzhaigou, Xi'an, Pingyao, Luoyang/Shaolin/Kaifeng.
Cheers!

I would go along with the earlier replies. You should see the Terracotta Army. As you have to change trains in Xi'an to get to Chengdu, you may have to stop over there for a day or two, anyway, as if you change trains, you have to rebook as if a new journey. Jiuzhaigou is a national park, which might be better reached from Chengdu. It is also expensive by Chinese standards, with an entry fee of about 300 yuan, or (say) $40. I think you will find that hiking there would be done on boardwalks, along with everyone else.
An alternative route to Chengdu is to go to Yichang and get a boat up the Yangtze to Chongching and get a bus/train from there to Chengdu.
Have fun!

#2, Jiuzhaigou could be easily reached by flights from Xi'an, Lanzhou and Chongqing as well. Overland is possible from Lanzhou but it would take a long time. Entrance fee is 220 RMB + 90 RMB bus = 310 RMB, assuming you don't have a student card. The boardwalks are there to protect the reserve -- how is it going to be a reserve if everyone's trampling over the plants?
Do NOT do the 3 Gorges cruise, whatever you do!!!
Cheers!