Shangri-La is a city located at 3200m above sea level in the Northern part of the Yunnan province. Shangri-La is a blend of Tibetan and Han culture. It is a short 3-hour bus journey from the Tiger Leaping Gorge. While the old town might not be the most interesting of all, Shangri-La is home to one of the most important monastery in southwest China.
The Ganden Sumsteling Gompa is a Tibetan monastery complex of 300 years old with over 600 monks. The inside of the monastery is much more impressive than the outside. A few other activities include wandering in the old town which has been massively rebuilt after a critical fire back in 2014, visiting the Zhuangjin Tong also known as the prayer wheel and visiting the Baji Si also known as the 100 chicken temple.
Even though it is an enjoyable city to visit, I would not make it a priority if you are running out of time or heading to Sishuan.