Best way to Tour for 10 people? and rainforest question

I am visiting Grenada with family of 10 visiting in January. (Ages 9 to 67)

The family are all chocolate obsessed, the kids want to see sugar cane and we like to get concentrate on unique places when we visit a country.

Right now I think we'd like to see (In order of importance) Belmont Estate, Nutmeg Processing Station, River Antoine Rum Distillery, Rainforest and generally get a feel for the island.

Can anyone suggest:

- best/least expensive way to tour

- have I missed anything important?

- amount of time we need

ALSO:: We are also stopping in St Lucia, Martinique, St Thomas and Antigua. So the spices are most important, but I have the impression that this is the best place to see true rainforest???? Or would another island be better?

Thanks!