I have to vote for the EXT 4X4 diesel passenger van, with a roof rack. Lots of room for little kids and all the stuff that comes with them, the ability to tow a small trailer to leave at base camp now.
Later It can evolve as the kids grow, to tow a larger more comfortable base camp (trailer) and still seat the kids and the friends you know they will want to come along.
Better to have enough space now, with the ability to grow, than to have them all crammed in and grumpy on a long drive.
That will kill the fun and the possibility of future trips in a hurry.
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