I actually did not think I would bring something new this year, as last year felt pretty comfortable all the way through.
But, seeing how I am always missing a "proper" chair when Marshalling, I have bought this:
http://www.korsholm.dk/dk/kinetic-rygsaeksstol.html (bought with a backrest)
And will also bring it to Le Mans, instead of my regular camping chair which I usually throw out when going home, and therefor will carry one less item with me around the circuit