You can also transfer to AC or SQ to redeem for Star Alliance, and having three programs to choose from is useful because the award charts differ. For example, NH (ANA) charges by distance, while the others are zone-based programs.
While AC does assess fuel surcharges on several carriers it does not on flights operated by UA, US and many other carriers. See here:
http://www.flyertalk.com/forum/air-c...rd-travel.html
Totally agree with mia that Air Canada often flies under the radar as being a sneaky good transfer partner....as long as you can use their miles to fly on airlines they don't charge fuel surcharges on (which can sometimes be difficult).
If you can do that though, they also allow 3 stopovers on their awards tickets, which is UNHEARD of nowadays, so you can really, really make some awesome value out of AC miles if you pick the right flights. Your flexibility may be limited, but the value is there!