Here are a few details about transport, departure times and costs from the trip from Korla to Beijing - I found that much of the info in the guidebooks was out of date. The prices are for the low season, and are in RMB, and the times are correct as at 23 December 2005. Just doing my little bit to help ...
Jiayuguan
Train from Korla 190 hard sleeper, 24 hours, departs 12 middayBuses to Dunhuang run 3x daily (8.30, 11.30, 16.30) so I guess they run as frequently in the opposite direction. Sleeper bus to Lanzhou departs 14.30.Accom. Xiongguan Hotel 50 for 3-bed dorm but NO showerInternet 4/hour diagonally opposite the Jiayuguan Hotel (15 min walk from Xiongguan) where staff can also book train tickets - almost essential!Sights - Overhanging Wall 21, Fort 60.Xi'an
Train from Jiayuguan ??! 144 from Lanzhou (hard sleeper). 24 hours whole trip, 2x daily, 1068 departs 12.20, 1044 depart 13.50Accom. plenty of YHA's in Xi'an (I don't recommend Flats of Renmin Hotel) - try http://www.travellerspoint.com/budget-accommodation-en-ci-1394.html Sights Bell Tower 15, South Gate 40, Famen Si 32, Terracotta Warriors 65, Qin's Tomb 25, Big Goose Pagoda 20, Lin Tong museum 24Beijing
Train from Xi'an 274 hard sleeper, 13.5 hours, last departure daily 21.15Accom. Downtown Backpackers Accommodation is highly recommended, 50 for 8-bed dorm + own shower, on hutong between Gulou Dongdajie and Di'anmen Dongdajie in centre of townInternet 10/hour at DowntownSights Forbidden City 40 + 40 audioguide + 10 eastern complex, Yong Ge 25, National Museum 30, TEmple of Heaven 30, Summer Palace 20