Originally Posted by
pinniped
In a J configuration, that means I'd attempt to have 1 window and 1 aisle in hand before I started thinking about trading. If it was a 2-3-2 and I had two middles, I'd just deal with us sitting apart. (On a 2-4-2, maybe you can get two middles together.) Two grown adults can fly on an airplane separated by a couple of rows. Both will arrive at the destination at (approximately) the same time.
I would add however that the middle seats of four really sucks on some carriers (yes, I mean you, UA) and is actually quite nicely secluded for couples on others (ie BA 747)
The same holds true for aisles on some aircraft in business class. All aisles are not the same on LH - the aisles in the centre section are much more desirable to many passengers because there is no need for someone to climb over a reclining passenger. And on the UA aircraft which are four across in J, I'll take a side aisle over a middle aisle.
And since you threw out UD, that is a whole other issue. Most people I think would value seats on UD very differently than in the main cabin. I might consider a move to the main cabin on a daytime flight on a BA 747, but if it is a night flight there is no way I would consider giving up my seat on UD (especially as one tends to need status to reserve those at time of booking)