So, first thing to know is that the total space being shown on the
DCL site
includes the balcony.
On the Wish, the Deluxe Family with Verandah is a 241sq ft cabin with a 43sq ft balcony.
The Deluxe Verandah is 200sq ft with a 43 sq ft balcony.
The only exception to the size of the balcony is if you get a Category 4E, in which case the balcony can be up to twice the size.
The 3rd (and possibly 2nd depending on your sleeping arrangement preferences) person will be on a pull-out sofa or a pull-down bed, so that extra space is really nice.
That said, the rooms on Disney are typically bigger than other cruise line rooms.
As far as within DCL, the rooms on the other ships are bigger than what's listed for the Wish.