A good way of measuring it might be the annual outside visitor count. If you can go someplace that sub-10,000 you're probably on to something, and sub-1,000 you really might be on to something (heck, that may be less than the top of Mt. Everest gets). Of course you also want interesting sights and/or culture.

I used to like to book award trips out of MNL on CO and their Micronesia island hopper, as back then you could go to islands like Kosrae, Pohnpei, and Majuro and count all the visitors on your fingers and toes. The places seemed frozen in time and had their problems, but also lots of charm.

The Pacific still has lots of underserved places. I learned not to say too much to locals about booking award trips on CO or NZ, as they could really bend your ear about fares they have to pay to go off-island. Most of the places are really great to visit, but you start to grasp what a great privilege it is to be able to leave,

All-time fave, though, had to be in 1997 in Jakarta when I was getting a bit bored and one day spent hours on end in a cybercafe (a novelty there then) on easySABRE trying to put together an eastbound trip. I got the last seat on Sempati on a 2-stopper red-eye (with meals on all segments) to Ambon, where I'd catch a PELNI boat that'd go through Manokwari and Biak to Jayapura, on the west side of New Guinea. Then a cargo plane in and out of the Baliem Valley, a pretty incredible place only "discovered" since 1954. Outside Wamena, most things were built without having nails. Also an amazing native culture. Then from Jayapura on Merpati to Ambon and a RT to the Bandas, the small cluster of islands where all the world's nutmeg came from for 200 years. So much history that cannon barrels were lying by the streets. Then Merpati again to Bali and 5 or so days of civilization.

Later on there'd be unrest in both Maluku and Papua, so I'm glad I went when I did. Also glad for getting to Angkor Wat in 1997 and Luang Prabang in 1998 before the crowds.