Originally Posted by
Swiss Tony
As an aside, having flown with our son, the first time at 10 weeks old and most recently long haul at 15 months old, I think the lower deck is probably better. It's more roomy, you have more storage space and that front cabin is very pleasant. I also think you get less of a DYKWIA/more child-friendly quotient on the main deck

Our son's not loud (yet, fortunately etc etc) but I can imagine sound travelling that much worse on the upper deck...
Having flown in both 14 and 64, my experience is that 64 A/B was much better and much more room, and the backward/forward config was a small trade off for the more room. 14 E/F with the bassinet we found was far too claustrophobic - for us not the infant
We did not have any DIKWIA and similar on the UD - but then again our daughter knows how to behave and we know how to travel with her without disrupting other pax. In fact i recall spilling champagne on one of those segments and being emabarassed - so I caused more problems than she did.