I have 3 nosey kids, and no closet space. So I wrap everything from BF and put it under the tree. I warn them, anything gets opened, or they mess with them,
1. I'll take the item back to the store and not get a replacement
2. Santa won't come with a surprise gift if they get too nosey!
Seems to work

Of course I am not that way with my youngest, she just turned 4, but my oldest two definitely know better <9 & 12>.
You could go to a grocery store when they are doing their nightstocking and get the big cereal boxes like from Kellogg's, and use the idea everyone gave above

Oh, and I would wrap the gifts before putting them in the box, just in case!