Congrats and happy planning!!!
Try to avoid Feb and March as those are considered pretty busy months- especially with school breaks and such...
I had a hard time picking a location too, we finally decided on ROR in Jamaica, but the Riu is actually pretty big with 850+ rooms, so that wouldnt be quite perfect for you! If you end up deciding that it doesnt matter if its a big hotel than I would suggest the ROR because it is all inclusive, in Jamaica!! and its kid friendly!!!!
This website will help you out a lot, no worries!!!