Thank you all for the responses.
Whilst I would like to get Elite benefits, it would not be the most important thing as I will most likely be the Gold Tier in the new program, which doesn't get me much anyway. For me the most important is to showcase Hawaii and USA to my wife and my small kids (aged 6 and 3), and let them have a good time, along with using up my 2 * 7-night certificates (if they are not converted into points by Marriott in August) which I can upgrade to level 8/9 if required. I am planning to use 1 at Oahu and one at either Maui or Big Island (which we haven't decide).
Having said that they would prefer to be centre of the action rather than driving back to Waikiki all the time. If we do stay at Waikiki I think we will spend one day driving up to North Shore as it seems to be nicer and quieter place.