I find those rectangular folded boxes absolutely great!
Unfortunately I discovered them too late, but if you haven’t begun yet (oops! ;-)), they are great for an Advent calendar, too ;-)
But take your time, I once made an Advent calendar from similar, but square boxes (instructions from a book) and it took foreeever to finish it.
I use it nearly every year though and it is still beautiful ;-)
And apart from that you can still use them for the Christmas gifts, I think that it would look wonderful, too :)