I was born and raised in Hawaii, and I attended UH-Manoa for my undergraduate studies. But I didn’t have the most mind-blowing social life, so take my post with a grain of salt or two.
I get the impression you may be a little too focused on the omg Hawaii aspect of going to grad school in Hawaii. It does sound good-- go to school, work to make ends meet, spend free time enjoying the beach and sun. But given the high cost of living on O’ahu, you will very likely be working more than you think you will, and consequently, you won’t have time to do the things you think you will. I knew very few students at even the undergraduate level who could simultaneously make good grades, work to support themselves, and have a decent, active life. It’s not impossible, but eventually something has to give, and for most people, not working or quitting school isn’t an option.
If I were you, I would make a visit to Hawaii to check out both the UH-Manoa and HPU campuses. UH-Manoa does not seem to have a military studies program, but I think you should visit it anyway to 1) see if there is anything else you would be interested in studying, and 2) have something to compare HPU with. From what I remember, HPU is a tiny school located in downtown Honolulu. Their location is really convenient, but you may find their resources lacking.
Hawaii is indeed an awesome place, but the reality of it is as a working grad student, you might not often be in a position to enjoy it.