Hi
JamieG - welcome to the BAEC corner of FT!
I think 2A/3A are excellent choices for a couple that are happy doing their own thing (IMHO), when it's daylight you've got the window, when you want time together there's plenty of room on the buddy seat. Bear in mind tho that the flight to SIN is also an overnight flight, so by November it'll be completely dark from takeoff, you'll have dinner, then you'll find many people will get a good nights sleep.
If you go for the middle seats, you will need to lean forward, but it's not too challenging IMHO, although we're both at least 6' tall!
Definitely go for the upper deck on the way back in CW, it's quieter, there's fewer seats, and you get to use the yuuuge bathrooms at the front (sadly just toilets, but still big). Personally, I like the window / aisle seats at row 53 or 59, as the person in the window will not have to climb over anyone (although the person in the aisle will still have that). Also, upstairs has loads of storage by the window.
As well as the A380 seat thread, you might want to also check out
http://www.flyertalk.com/forum/briti...ies-first.html and
http://www.flyertalk.com/forum/briti...lub-world.html
Enjoy!