Don't worry about the 3-4-3 seat arrangement on their 777. These 777-200's are used only on short-haul flights. All transpacific flights are operated by 747-400's which has a decent seat pitch in Y class. For service and food, it'll be good especially when compared to US-based airlines.

You'll get 100% mileague accrual even in Y class. No problem about that.