I have also seen reference in CO charts to "Micronesia."

There is no non-stop to Guam. There is a "direct" flight on CO, which makes a stop at NRT (Narita, Japan) before continuing on to IAH, with flight numbers CO6/CO7. If you take this flight on a paid basis, you lose about 1400 miles because airlines credit mileage on direct flights as if they were non-stop.

CO also flies through HNL.

On paid OZ (Asiana) flights, I'm not sure one can currently fly to SPN (or on KE to GUM), because of U.S. anti-cabotage laws prohibiting foreign carriers from transporting passengers between two U.S. locations. (Guam and the CNMI are U.S. territories.) A few years ago, OZ got hit with a big fine for this, so to be "safe" they don't even list SPN on their website, which makes it harder to book ICN-SPN flights -- they must be done offline.

Unfortunately, because this part of the country is remotely located, there is no really inexpensive way to get here. The best deals over the past couple of years have been some NW promotions and internet fare sales during the fall and winter.

I've found redeeming miles on NW has been easier than on CO. There is a good connection DTW-NGO, and then NGO-SPN. I think if you fly DTW-NRT, you will have to overnight in Tokyo both directions before doing the NRT-GUM segment or vice versa.

On CO, it is generally cheaper to fly to MNL, on the flights that go through GUM. Perhaps you can get a GUM "stopover," and continue on to MNL for a couple of days?