For me, the itineraries are key now as many other aspects of cruising has slipped or gone or just don't appeal so much anymore. Same shows same itineraries, etc.
With that in mind, NCL, HAL and Azamara seem to have the better and much more varied itineraries. They are all in USD though.
Yes, it doesn't happen with friends but it can happen with colleagues and acquaintances and occasionally extended family. CC friends may well fit into the friends group or the acquaintances group depending on how well you know them.
When I was there last you needed to buy tokens for any purchases on the island, like food or drinks or massages etc. You could buy the tokens with Kina or AUD.
I have been stung a few times when tallying up the bill to be split and some people have left early and then the restaurant has come in with an extra charge like cakage, or corkage or even someone charging drinks to the table.