Hi,
As a specialist in Liveaboard Operation in Maldives, just wanted to add few words. Different Liveaboards have different class, If its for Maldives i would suggest a 100ft liveaboard , which is the most convenient size of liveaboard. And the boat should not exceed the cabin more then 7 for the best comfort and the service. Total number of pax should be 14 pax. This is an ideal boat size and number of clients to do a good tour.
Re the number of nights. Ofcause longer the tour the more you get to explore and visit more unexplored area of Maldives. Normal tours is based on 7 nights and can do certian area due to days limitation.
If you are a repeater i suggest go for a longer tour 9 nights minimum , or 12 nights. Maybe 14 nights is a bit long but it all depends on the group preference.
Hope i was able to offer some tips which can be usefull .
cheers