Not sure if you've already picked a place, but my uncle is a travel agent who knows the Director of Sales at the Maui Visitors Bureau. He suggested getting married at Old Lahaina Luau, and then all of the guests can stay for the drinks, luau, and dinner. From their experience, this is the best quality luau in terms of food and location. http://www,oldlahainaluau.com
They also recommended an excellent hotel, good price (although I think it's still a little pricey) and right on the beach: http://www.royallahaina.com
I ended up sticking with a destination beach wedding in Honolulu for this upcoming Feb 2014. Still on the search for a beachside ceremony site, so any suggestions would be more than welcome!