We are doing a custom trip, though I won't go into the details here as in case the boys read this. Can't stop even the little one reading everything in site right now! Anyway, we booked flights and accomodation and everything, only thing we could not book was the transfer between the two locations, as no flights had been released yet. They have now, but there are no direct flights between the two places were are going! Two choices, one is an indirect flight, having to change, which is mental as it's quite a short trip. The other is a three hour drive to another city. We're going for that one, it should add an extra bit of fun on, see a bit more, and not be too much hassle. It'll be a bit cheaper, and we'll have the car anyway.
I will be back with more details when we have announced the trip to the boys, though we're not doing that until after this year's trip to Center Parcs so one trip doesn't outshine the other.