I’ve flown to/from both Haneda and Tokyo and the JAL lounge at Haneda is the best...champagne room, aviation museum/library, John Lobb shoe shine. Wonderful!
I was in F on the 777 and thought it was more than adequate. Winter schedule so didn’t have any choice. You could end up getting an aircraft change from the 787 anyway so choose the flight times and airports which work best for your trip.