Is Guam on the East or West Coast?

Neither. Guam is a U.S. territory in the western Pacific Ocean (Micronesia), ~3,800 mi west of Hawaii, ~1,500 mi east of Manila, ~1,600 mi south of Tokyo.

It is the largest, southernmost island in the Mariana Islands chain. Time zone: Chamorro Standard Time (UTC+10) – 14–17 hours ahead of US East/West Coasts.

Politically: Organized, unincorporated territory. Residents are US citizens. Strategic military hub (Andersen AFB, Naval Base Guam).