Originally Posted by Microwave

You could do this trip either way. All-airline awards are one-way, so SFO-HND would run you 50,000 in J or 62,500 in F, and HKG-SFO would set you back 55,000 in J or 67,500 in F. Overall, the trip would be 105,000 miles for J or 130,000 miles in F, and you'd be responsible for your own way within Japan and between Japan and Hong Kong.

Another option would be to go with a oneworld distance-based award. If you just wanted to route SFO-HND-HKG-SFO, you'd be flying 13,891 BIS miles, which equates to 115,000 miles in J or 150,000 miles in F. To put it more clearly, you'd be paying a premium of 10-20,000 miles to include that one intra-Asia flight. Depending on how much domestic traveling you'll be doing in Japan, you could bump to the next distance level on the oneworld chart and be free to travel up to 20,000 BIS miles (with standard rules: 16 segments maximum, no transiting same city more than twice, no stopovers in the same city more than once, etc.), which would cost you 130,000 miles in J or 180,000 miles in F. This would allow you to fly something like SFO-HND-HIJ-HND-CTS-KIX-HKG-SFO (be creative--you could throw in other Aisan destinations as well, like ICN or TPE) and have all your travel covered. So the answer to your question really depends on on how many miles you want to spend, how long you'll have, and what you want to do in Japan and the rest of Asia. Hope this helps!