Hi,
I flew on a 777 from LHR to ATL a few weeks ago and a 747-400 from SFO to LHR, both flights with BA (WT premium outbound to the states and cattle flying back).
I can't say there were any issues with air on the 777, if anything I was a little chilly and the air was certainly much better than what I get in my office working for a blue chip company. We had a bumpy landing due to cross-wind but the aircraft itself was ok. On the 747-400 I found it impossible to get any sleep flying cattle, compared to a good few hours the last time I flew Virgin out of LAX.
On the 777 flight however BA messed up the special meal order and the in-flight entertainment system didn't work until 2 hours into a 9 hour flight. Flying premium in row 24 I knew about it every single time someone used the lavatory in the middle of the aircraft as the vacuum flush makes enough noise to be audible when wearing headphones, despite the engine noise. I can't say I noticed any wallowing or rocking on the T7, in fairness it was a very smooth flight until the airbrakes were deployed on decent. For pure comfort and better service however I would choose to fly Virgin's Airbus A340 is in a different league to BA's 777.