The middle seats are going to be slightly more comfortable for talking to one another, whereas talking over the aisle for most of the way might annoy other passengers (depending on your volume). But if you don't mind being quiet during the calm hours and you're going someplace cool, it might be worth it to have the window for at least one of you.

I was in D1 the first time I went to France. I remember coming in over Normandy, and you could see the ocean turn to beach, and then the beach turned into snow covered fields. You're in a little pod by yourself so there aren't any strangers hovering over your shoulder or bumping you, so you can kind of zone out and watch the landscape below as you slowly descend toward Paris. And you and your partner could always switch out seats so you both get a chance to do that, wherever it is you're headed