I agree with LarryU. The premium transcons (JFK-LAX/SFO) used to be tops in service, but now the service is nothing special. The 762 F seats are nothing to look forward to, though the extra legroom and recline and in-seat PTV is much nicer than F on the 737/757/319/320/etc. However, AA still keeps true international aircraft with real International Flagship Service on these routes.

Otherwise, the best route for service is any with a good crew. That now makes all the difference. Food service is nice, but it doesn't mean much if the crew doesn't prepare it. I'm happier on a one-hour flight with an attentive crew who keeps refilling drinks and snacks from wheels-up to wheels-down than I am on a transcon with full meal service but a prison matron crew who disappears into the galley after a rushed meal.