I have recently travelled on the BA A380. I don't want to sound pessimistic, but keep your expectations low. The upper deck is very cramped. I had 50J/K. The aisle seat is literally IN the aisle (actually basically in the stairwell) and everytime someone comes through the curtain, they are on top of you. 50K has no window, so it feels claustrophobic and cramped. My parents flew in 14J/K a few weeks later (lower deck) and as regular QF travellers, they were also decidly unimpressed. The yin/yang arrangements has benefits, but the biggest issue is the clambering over the person behind you. Not fun.
Overall, I feel BA have missed the mark on this bird by cramming too many seats in. I will be seeking out other aircraft for the return journey.
To assist you, the reason my parents moved to the lower deck, was based on the comment by the crew on my flight that the lower deck has a better crew to pax ratio (5 for the cabin instead of 4 upstairs - where there are actually more seats) and the aisle is wider, making for a slightly better experience for the aisle passenger. I would suggest you try the 2 middle seats dowstairs. Row 14 if you can get it as I believe that's the one that you don't have to climb over anyone! I've also heard the middle seats feel more spacious - like a double bed. So if you can live with the staring at the strangers in the aisles, then these may be the pick!
I hope this feedback helps. As I said, I don't mean to deflate your excitement, but I too was very keen to try the A380 and was dissapointed.