Welcome dinners are wonderful and always such a good time for the couple and their guests -- without the stress or any timelines of the wedding day
If you're on an AI resort, plan to have a gathering at one of the restaurants or even a bar to keep is casual. If you're on a private property (condo/villa), plan something super casual but festive -- a taco bar is always easy! Or even propose it as a meet and greet for all your guests with just drinks and appetizers. We actually shot a wedding where all the guests were invited to a local restaurant that sectioned off an area for the party and the couple provided non-alcoholic drinks and appetizers, for those who wanted to eat, they had to order. It was fabulous and festive!
Everyone is going to have a great time regardless of how formal or casual it is, they'll all be pumped in anticipation of the big day!!! Oh and all-white party is an awesome idea, since it will just be you and your hubby-to-be in all white come the Wedding Day!!!