Mark
I've done a lot of long haul flights, and never had a major problem with jet lag.
Having said that I know people who take at least a week to feel "normal" and it does seem to become more of a problem as you get older.
As the cost of travel becomes more expensive, holiday companies are going clearly going to cut the length of holidays, thereby cutting out a couple of nights in hotels and containing their prices, but still try to pack the same amount in, making the whole thing more hectic, JY have done this with several holidays, but are by no means alone in this approach.
You can do the obvious things, like put your watch to the destination time as soon as you get on the plane, plus don't drink any alcohol on the plane, and I'm sure that will help, but the only real way to find out how you react to a long haul flight is to do the holiday.
Hope that helps.
Stuart