Opx, the weather in august was fine
Lijiang was like a late spring in Tuscany with warm sunny days and occasionally showers.
Ringha is colder (especially in the evening).
Treks are fine especially when you have the chance to meet locals (who are very nice) in places off the beaten track. The hotel guides drive you around with a comfortable jeep. The guide in Lijiang was impossible to understand and sometimes we were so tired about asking to repeat that we pretended do understand even if we didn't. The guide in Ringha was much better.
Treks are easy the only thing is that the altitude is always quite high.
IMO you should ask to do something off the beaten track (the tourists are everywhere). As I said before, Lamayuru and the glacier of the Jade Dragon are impressive. On the other hand, the tiger leaping gorge (which is the daytrip while driving from Lijiang to Ringa was quite disappointing).