The Muslim food street is just by the drum tower. I ate there a lot. You will probably come across the dumpling banquet at DeFaChang as being one must-eat in Xi'an. I did not enjoy my meal there. The restaurant is located by the square between the Drum and Bell Towers.
Of the several tourist bus routes that go out of the city proper, lines 5, 3, 2, 4, 1 are how I rank in descending order of importance. This is not to say that the closer attractions should be neglected. These are Small & Big Wild Goose Pagodas, and the provincial museum which are now accessible by MRT too.
Line 2's significance is the ancient Famen Temple. However this site is overwhelmed by the massive new temple which in my opinion is done in bad taste. The sore thing is that the ancient artifacts unearthed at the ancient temple is now exhibited at the new complex. Make your choice whether you want to go on Line 2 at all.
Line 1 requires an overnight trip unless you want to make a daytrip, leaving Xi'an on the 7am bus with the intent to return with the 5pm ride. This means one has to make both the ascent and the descent by cable car. Nowadays there should be a direct high-speed train from Xi'an North railway station. This train station is the terminal for MRT Line 2 as well. This route should save a lot of time, making a day-trip a real possibility.
For Line 5, don't neglect to visit Huaqing Spring. The mausoleum of the Qin emperor is a waste of time. The excavation at the Museum of Qin Terra-cotta Warriors and Horses has resumed, which means visitors shall be able to see archaeologists at work.
