I fly to Guam from LAX 5-6 times a year. LAX-HNL-GUM is the most efficient way for me. However, if there are IRROPs involving LAX-HNL, then LAX-NRT-GUM is an alternative that will get you into GUM at 1am as opposed to 6-7 pm.

In order To be rerouted through NRT you need a passport. Otherwise you can be stuck in HNL for a day.
Similarly, if the GUM-HNL flight is canceled, a passport would be needed to go back via NRT.