I have always found that putting PJ's on BEFORE take-off is the most sure-fire way to ensure that your plane will go tech !

As someone who does waaaaay too much longhaul travel..... (see a few weeks in the life of thead).... my secret is

1) Travel in whatever is comfy - aim for overnight flights
2) If you want to feel fresher after waking up, take lightweight set of clothes in hand luggage and some body spray/deoderant - it's amazing what just putting on fresh clothes and underwear does for your self esteem.
3) Ensure you are staying in a hotel with early checkin and 1hr pressing service (most 5* hotels offer this.. and for good reason !)
4) Go straight to hotel off flight.... press suits whilst in shower....
5) Arrive at meeting looking like you're fresh and awake

You can almost achieve this if you get off a flight at LHR that allows you access to the arrivals lounge, they'll do a pressing service there, or you'll find most airport hotels offer it if there's half decent (Sofitel does if you take a day room).

Ultimatley it involves investment (£££) however as someone who's always recieved positive praise for how professionally turned out I look when people know I've as good as stepped off a 12hr flight... it's clear that that investment is paying dividends.

Up to you of course - that's just my take on it.

Ed