Telephone check-in helps, regardless of your BAEC status -- gold, silver or blue. I'm merely blue, but checked in via phone last month for my LHR-SEA trip in coach and got 28C -- an aisle seat on the second row of the 742's WT cabin -- as much as I could expect for the money (discount fare).

I can't speak to the 777s but on the 744s look for 17C or so -- and on the 742s 28C or 28H.