YVR to HKG:

1) US Airways would require the least number of miles, ie 60K miles R/T or if you got a little more miles, 90K in Business is a great deal. You can use Air Canada for a direct flight reedeeming it on US Airways. Other partners you could use are UA, ANA, Thai, Asiana and SQ but you need to connect in the US and possibly one more Asian city for these options

2) UA - 65K miles R/T but you can book all the partner airlines on UA website (again try AC first for a direct flight to HK) which you can't do with US Airways, thereby avoiding the reservation fee and Partner award fee charged by US Airways. With UA, you can also reserve one way for 32.5K if you are not sure about the return date. You can use the same partners listed in (1) above since they are all part of Star Alliance.

3) Delta - 70K miles R/T but hard to find seats at this redemption level on Delta. You might have better luck with Korean Airlines which is their Asian partner or you could try China Airlines (another partner) as well as China Eastern and China Southern. But the taxes and fees are generally higher on Delta partners than on Star Alliance airlines.

As for issuing the award ticket for your sister, if you have enough miles in your account, you can issue a ticket in her name as well.

Good luck!