Definitely a couple of extra pillows and blankets to pad out the bed a bit.
Crikey, when we've been to Center Parcs in the past we've taken half the house, but honestly found we needed it. Also found it was cheaper if we took plenty of basics with us like jars of sauce, tins, pasta, rice, tuna etc to add fresh stuff to from the supermarket down the road.
Music for the CD player, toilet roll, condiments, snacks, wet weather gear, indoor stuff to do, definitely a camera, soap powder for hand washing the odd thing. Are you taking your bikes? Don't forget your locks and helmets if you do, or even if you're hiring. They give you locks when you hire a bike, but they're a wee bit flimsy.
And most importantly don't forget your oh-so-important list of why your children don't need to do the 101 expensive things on offer- and practice repeating beforehand.
Top tips we found when we went last year:
If you go and play badminton in the early evenings there is never anybody on the courts and they let us play for free each night.
Crazy golf's pretty cheap and good fun. But don't get hoodwinked into hiring a putter for everyone. Just hire a couple and share.
But then I'm a cheapskate...
Have a fab holiday, we're going again next March and I can't wait.