I will tell you that Infinity has awesome aft balconies (better than Solstice class) and so I am biased towards the SV option. The SV balconies are large (they have a lot of depth) and you have a choice of being on the portion of the balcony that has an awning above you if you want shade (or shelter from the rain) and you can also choose an area of the balcony (closer to the rail) if you want sun. The SV balcony is easily large enough for all 4 of you to be out on the balcony at the same time with plenty of room to spare. If you choose an SV, I prefer to stay away from Deck 9 since there is a public deck above you. Deck 7 and 8 are great although I am partial to Deck 8 for no good reason.
We have been on 14 Celebrity cruises with our two kids but have always been in one cabin. If we were to split up into two cabins, I dislike Option A (price) and Option C (don't want to be split apart on different decks). I would prefer the Option B arrangement.
Aft balconies on Summit (Infinity sister), Jan 2015, St Maarten.