Fully agree with all the positive comments on Labrang - for an expat who lives in Beijing, this was a really special experience. Make an effort to get to Langmusi as well, very special place, and even more "off-the-beaten track".
I'd like to invite anyone thinking of getting a guide to Xiahe/Langmusi and regions in-between to consider getting in touch with Clary at Nomad Travel. Clary is Dutch, has lived in the region for many years, is married to a Tibetan gentleman and has many amazing insights into the region and its people which she generously shares. If you want a first-hand glimpse and a deeper understanding of the fast-disappearing Tibetan nomadic lifestyle, and some of the complexities of modern-day China, she is the one to turn to. She arranged all hotels, transport etc etc. Brilliant and well worth it. Our trip was fly in to Langzhou and drive to Xiahe, two nights Xiahe, drive to Langmusi, two nights Langmusi, drive back to Xiahe, one night Xiahe, then drive back to Langzhou and fly 'home' to Beijing.
Also, don't let all the negative complaints about the hotels in Xiahe etc stop you from going. These reviews are no doubt mostly accurate (my experiences were roughly similar), but these hotels are certainly no worse than anywhere else in rural China! And the payoff for gettting to Xiahe and Lamngmusi is immeasurable - certainly worth a night or two of mild discomfort about which you can then relate to your friends for years to come.