The Almond resorts in Barbados and St Lucia have kids club. I think end of August until October can be hurricane season so it's probably worth doing a bit of research into which islands are more likely to be effected. I've taken my DC to Jamaica, St Lucia, Cuba and Dominican Republic and think the Caribbean is a great family destination.
Oh Pagwatch I am sorry. I read the rules carefully as I did not want to annoy or offend anyone and it said they were happy for you to post links as long as you were not spamming. I genuinely thought I was helping, as a mum who knows how hard it is to find places to take children, I was merely offering help. I will not post again if I misread the rules. Apologies.