You can have a great time on Moloka`i for a month -- if you go with some different presuppositions than what folks often have in mind when they think of "Hawai`i vacation."
First of all, tensions are running high on Moloka`i right now. Google "lau point molokai" or "molokai master plan" and read some news stories. I don't pretend to know what the answer is, but the ante has been upped significantly with the closing of Moloka`i Ranch -- which employed a large percentage of island folks. So there's a certain grimness in the air on Moloka`i. This can occasionally translate into resentment of tourists who clearly have all the money in the world (or they're perceived that way).
Second, over the last few years, speculators and part-time mainlander folks have basically significantly damaged the east Moloka`i community. There are some details in my trip report
here (and you might find it of interest in general).
Third, my admittedly brief experience on Moloka`i is that it is the tourists who come for the "unspoiled real Hawai`i" experience and then complain because every grocery/convenience store on the island closes by 8:30 p.m., etc., etc., who are given the most stink-eye. There are also no gourmet restaurants on Moloka`i, but there are some good, decent "local-kine" places.
Fourth, the very best way, in my opinion to experience the "real Moloka`i" is to go (if you're into this sort of thing), one of the local churches for Sunday worship.
Moloka`i is different: it's only got about 7000 residents. It's a "working class" place with very strong and long family traditions. It's kind of a hard-scrabble place and my impression is that it doesn't get the share of Maui county monies that could help some of its infrastructure problems (facilities at parks, e.g.) It's also the only island (other than Ni`ihau, of course) that is majority ethnic Hawai`ian.
Hope those ruminations help. For me: I'd go back in a minute and gladly stay a month.