Just back from our China visit and have some comments on Xi'an that others might find useful!
We stayed at the Sofitel which is in a great location, walking distance to Drum tower, Bell tower and Muslim quarter. There is no need for driver or guide to visit these (if like us you prefer to adventure independantly). We did the Drum and Bell towers on a Saturday morning and there were shows in both. This was an unexpected bonus! the muslim shopping street is lovely and very pleasant to stroll down - leading straight to the drum tower.
Terracotta warriors - our taxi driver did not know the way and had to stop several times to ask directions!! However we got there OK! Picked up a guide inside. This is the first time we have ever hired a guide, and we wished we hadn't. Although she was nice, and knowledgeable, we felt a bit rushed (and of course were steered into the gift shops and into a particular restaurant for lunch afterwards.) They actually have an audio guide system (like at the Forbidden City in Beijing), which we probably should have gone with.
We caught the bus back to Xi'an Railway Station for 7 yuan each! (We knew it was the right bus because the conductor said "Xi'an?!" and beckoned us on board (I mean where else would three western tourists be heading??!!) From here we just walked back to the hotel.
As always, having a good map and a well located hotel made all the difference!
Finally some advice about the "famous dumpling restaurant". It is in a shopping complex across the road from the Bell Tower and therefore easy to walk to if you are staying in the centre of town. Just ask the hotel to write the name down for you, and passersby will help you find it! The better restaurant is upstairs (there is a cheap and cheerful restaurant down stairs with a more limited menu).
Finally, finally - eating options are limited (and expensive) once you have gone through customs at Xi'an airport.
have fun!