This is how we do it - person that buys the ticket gets the UG. I am more likely to clear than my TH, and if she bought the ticket, then she deserves the first UG. In this case, I will move from my aisle to get her a window. If she clears later, then I take what is left. She's been known to downgrade back to window seat incoach if she clears into a middle seat or the middle section on a wide body. I do not understand the need to sit together, but maybe that is just me.