I used to like the block adajcent seat policy when it was in use,
I have learnt over time, to always ask how full the plane is and if there are any rows with empty seats, I know a lot of people are concerned about sitting towards the front of the plane, but for me, if I get a row to myself in the back, I am taking it.
I have also go on the computers at AC and checked the load and a added tip if your flying BA, I have them check 1 hour prior to the flight, it seems that it the time that all the passengers have already checked in, this way I know for sure that the seat is all mine