For Star Alliance, Guam and Saipan are both considered North Asia, which is good. On Star Alliance you can get to Guam via Osaka on ANA for 60k miles. You can get to Saipan via Seoul on Asiana for the same miles, and then continue on to Guam on CO with a paid ticket. The reason why it's good that Guam and Saipan are considered North Asia under Star Alliance, is that you can travel for 20k miles to/from Guam or Saipan to Japan, South Korea, or China.