The Bay Area doesn't have that much food from Northwestern China, but we've got about a dozen places now that specialize in Xinjiang-style grilled skewers. These skewers are seasoned with salt, spices such as cumin, fennel, and ground chilies, and sesame oil, and have likely come here due to their popularity as street food in Beijing and throughout China. The skewers are inexpensive, spicy, and good with beer-- they attract a younger crowd.
Xinjiang-style skewer places are concentrated in the South Bay and Southwestern Alameda county (I-skewers and Beijing BBQ in SF closed, as did Street Food in San Mateo). They typically give you a paper menu to check off whether you want lamb, chicken parts, offal, vegetables, grilled steamed bread, etc. You can also get a side of Beijing-style yogurt to tame the dry spices.
At the places I've been to, it seems like every item on the menu gets the same spice mix. Do any local places vary their seasonings, and is it common to do so in China? Is the style more through a Beijing (or wherever) lens, or is it like something you'd encounter in Xinjiang?
The following places have menu sections devoted to skewers and have writeups on Chowhound. I am excluding restaurants that only a token skewer or two.
Beijing Restaurant (Excelsior, SF) http://chowhound.chow.com/topics/856576
Chef Yang’s BBQ (Cupertino) http://chowhound.chow.com/topics/848764
Hankow Cuisine (Cupertino) http://chowhound.chow.com/topics/1004619
Little Shen Yang (Union City) http://chowhound.chow.com/topics/554559
Made in China (Parkside, SF) http://chowhound.chow.com/topics/966672
I found these places on y*lp, and some have more desirable photos than others:
Aceking Music Restaurant (Newark)
BBQ Factory (Fremont)
FT BBQ (Milpitas)
GG Skewers (Fremont)
Smiling BBQ (San Bruno)
TLT BBQ (Newark, San Mateo)
Potentially this place, which hasn't opened yet:
Underground Grill Kings (Outer Sunset, SF): Taiwanese style skewers http://chowhound.chow.com/topics/1008080