That's a good plan, window and aisle in rows next to each other. That way, they'll swap exact same seat for exact same seat. Good chance they're both traveling alone.

The advantages to the bulkhead are less in premium cabins. I also felt sorry for parents having to cart kids up and down the aisle, crying, needing a change, etc. More discreet in rows further back. Also, the advantage of having toys and stuff near by. The few times I've nabbed a bulkhead, I have been able to tuck a small bag of "essentials" under the bar, under my seat that I could grab myself after take-off...