Personally, I love long haul, just check in early, try and get a bulkhead or exit row seat to give that bit extra room....
If you can, try and get an upgrade to the next class, it's always worth being really nice and polite to check in staff on long haul flights, I have blagged an upgrade 6 times (5 times with BA and once with Cathay) just by being polite and courteous to the girl at check in and then saying "I know this is really cheeky, but what are my chances of an upgrade?" This only really works if you are flying alone or with one other person maximum. I tell you, you wouldn't believe the difference it makes on a long flight to be in an Economy Plus or Business class seat!
The carrier makes a massive difference as well. The Asian airlines have far better service and food I find but they tend to have far more languages to serve so it reduces the amount of English entertainment channels.... I know you are native English speaking so you will have a better choice of movies and entertainment with Air NZ, Quantas, Virgin or BA. Also if you are flying on a stop flight they tend to change the movies after the stopover so don't think "Oh, I will watch that movie after the layover!" Of course you may be changing airlines halfway so that makes things fun, I have flown Auckland to London via LA with Air NZ for the first leg and then Northwest to Gatwick.... Choose Air NZ all the way if you get the choice! LOL