This is a 'chat room' - why not call RCI direct and ask them 0844 493303.
I think that this would be a splendid way to celebrate. With that many adults you'll be able to do most things and look after the "baby" (you give no age) and I am sure that as it's RCI you'll be surprised how little you see of the child as they are superb with children. It would also be a wise choice to go out of Southampton as there is no flying involved although the water may have a few lumps in it for the first bit. There are "Family Cabins which have more space and large balconies which might be worth your consideration although these along with the adjoining cabins are always the first to go, but a large number of cabins have connecting doors as well. Co to the Royal Caribbean International web site and look at the deck plans and get a brochure where so much more will be explained.......They'll all love it....Leanne Dow.
Or alternately....ignore the above answer and wait until the helpful people on this site give you some suggestions from their own experience of cabins etc on RCI, that is much more helpful then calling RCI as they will be doing a sales pitch on you.
It depends on your budget and how many you want in each cabin. You could have up to 4 people in one cabin, in which case you'll only need 2 cabins bringing the cost down. These cabins could be adjacent, interconnecting or across the corridor depending on your preference. Alternatively you could book three cabins for more space but obviously the price will increase. I believe there are family cabins sleeping more people, but have never booked that type. Don't forget that the baby and child will usually pay the 3/4th person price
We like to book the lowest deck balcony cabin, midship for less motion but the Independence is so big you probably won't feel much anywa.
Independence is almost sold out of all 3/4 berth rooms for the peak holiday sailings. 28jun has one room left, 12jul has 4, 26jul sold out, 9aug sold out.