G'day,
Sorry, no tips on the north coast -- however if you have the time i would make another suggestion.
Have you heard of a village called Malevu in the Yasawas?
If you've got the time, I would spend the last night in the village of Malevu -- perhaps it is not that practical for you as the boat to get there leaves from Nadi and takes about 3-4 hours -- it is such a beautiful place but if you've got the time i would make the journey...if you want more info about staying with the local community in Malevu go to http://www.fijibure.com/yasawa.htm
Click on the village -- the main website www.fijibure.com gives info about how to stay in local communities in Fiji through village homestays...
Otherwise hope your last night is memorable!
Good luck