Lang Son is not the destination for international tourists. However, there are so many guesthouses, mihi hotels and a few 3-4 star hotels to stay if you needs to spend a night in this city. Below are some suggestions:
1. Muong Thanh hotel: Opened in 2010, this is the only 4 star hotel in town with 124 rooms, 2 restaurants, bar cafe view, spa, swimming pool, tennis course. Muong Thanh hotel should be your first choice.
2. Van Xuan hotel: Centrally located with nice lake view and it is convenient to reach Ky Lua market, local restaurants and shops.
3. Phu Quy hotel: With over 70 rooms, fully equiped with AC, fridge, bathtub and a pacious restaurant serving local and Vietnamese dishes. Phu Quy is a good hotel to stay for a group tour.
4. Kim Sơn hotel: Not far from Ky Lua night market with 50 rooms, Kim Son hotel is rated 2 stars, having AC, fridge, tivi, free internet wifi.
5. Hoang Thinh hotel: Close to Dong Kinh and Ky Lua market, the hotel rated 2 stars and fully equiped with modern facilities.
6. Dimond Hotel Lang Son: Having 40 rooms and professtional staff, the hotel's restaurant serves Vietnamese and Chinese dishes.
Note: It is easy to find some more information of hotels in Lang Son on google, but it is always best to contact a local Vietnam travel agent in Hanoi for advice.