Cargo box recommendations?

Hi all,

Looking to pick up a set of cross bars and a cargo box for summertime camping.

Gear to haul: Tent, sleeping bags, food, clothes, cooking gear etc. for two adults and an infant and a toddler.

I know that BMW sells their own, but I'm guessing it's just someone else's with a BMW sticker stuck on the side (and 50% markup). Am I wrong?

What style to get? Anything to stay away from? I was thinking of getting the long narrow kind (think ski box) but I also see wider ones as well. If I get the narrow one, will I be disappointed with the space?


Any tips/stories much appreciated,

Darren.