My wife and I play the "Who's sleeping on the inside, so i don't get an elbow in the face or a knee to the grion everytime you have to get up," game. Our aft is big, but you have to crawl in and out of it and the person on the inside or furthest aft, is always crawling over the other to get out.
Plenty of room to sit up and read, but no room from about the waist down as it tucks under the cockpit.
A centerline Queen would be a welcome addition to our next boat.
I am finding that around 42', aft cockpit, they start to become available either in the aft or the forward cabin, it doesn't matter to me, I just want both people to have access from each side of the berth.
Remeber, I am speaking from a Costal Cruiser view point.
Courtney is My Hero
If a man is to be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most - E.B. White