Xigatse prerecture is in Central Tibet. It has numerous places of interest for tourists, and has good public transportation by Tibetan standards.
Cities, Towns, & Villages
Xigatse: the capital, and the only real city in the prefecture.
Sakya: a large village with an important old monastery.
Dingre: the closest town, on the "highway" to Nepal, to Mount Everest. There are a good selection of guest houses here, and it's a good place to spend the night and view Everest. It's also possible to trek from here to Everest back camp, with camping equipment in about four days.
Latse:(aka: Chushar), minor town with little tourist interest, but important for transport. It's as far as you can go on public transportation to Mount Kailash or Nepal (though you may get farther to Nepal). It's got a few guesthouses, and lots of shops.