To bubble or not to bubble - pt II

Help!
I'm off to Vegas in April. Seat selection opens tomorrow. However the seat map is already showing (can't select anything though) and it's a Heathrow 747. As I've only ever flown on the LGW fleet, I've no clue which seat to go for. On the LGW 747s, my preference is 6a for the privacy.
What d'ya reckon?
Paul
I'm off to Vegas in April. Seat selection opens tomorrow. However the seat map is already showing (can't select anything though) and it's a Heathrow 747. As I've only ever flown on the LGW fleet, I've no clue which seat to go for. On the LGW 747s, my preference is 6a for the privacy.
What d'ya reckon?
Paul