Guam is doomed because almost everything is imported, especially food. I was born there and lived there in the mid-70's (when people ask what the hell is wrong with me I just tell them "puberty on Guam").
Unlike Hawaii there is no fishing fleet and very little local farming. No cattle, only a few water oxen and a handful of wild pigs/goats. Mom tried to grow tomatoes and corn, heavy rains smashed the plants just before they were ready to harvest and almost everything was lost.
Guam is home to B-52s, B-2s, and a submarine base. The island also serves to protect the Marianas but you guys will have to deal with refugees coming from Oceania and the Philippines.