Just think of the parties you could host out there! Since you already have 2 of the 3 'Outside Deck' wings, (Storage Room & Armory) you might as well give your family a complete wrap around deck by building the bedrooms. Family will then take those beds, leaving the upstairs beds for your staff.
If you build the West Wing bedroom, 3 more beds are available: a double & 2 singles. Children get preferential use of the West Upstairs room. Your spouse gets preferential use of the East Upstairs Room. Without the 'Bedroom Wing' your house will be able to have a double bed in the East Bedroom and two single beds in the West Bedroom. of course, with the right mod, anything is be possible.
You can only change your choice of a wing before you build the doors from the main hall, after that the wing is fixed.
