I've been on four different UA 777s and a couple BA 777s. The nice thing about the seating arrangement is that there are only two seats along the right/left sides, with 5 in the middle section. The thing that makes flying the 777 enjoyable, in part, are the seat-back video screens. Interestingly, the older UA 777s (i.e. N772UA) have them, but newer ones (i.e. N795UA) don't.
I also got to sit in the cockpit of a BA 777 from Boston to London. We were out over the Atlantic, approaching Ireland, and I was allowed to sit with the crew for about a half-hour. As we were on auto pilot at 37000 feet, there wasn't much for the crew to do but chat with me. It was great. That particular plane was G-VIIG...one of BA's newer IGW versions. I flew that plane for the first time in the fall of 1997 and once again this past May, on a flight from London back to Boston.