Thread jack -
Stuff any empty spots with bubble wrap. When the inevitable souvenirs and Christmas presents start filling the gaps, the bubble wrap can either be thrown away or used to wrap fragile items.
Great idea! I have a friend who told me that when she goes on a trip she takes only her oldest, rattiest undies and throws them away each day and has room going home for souvenirs.
I read an article once that suggested when going self-catering to take the oldes, rattiest, towels/tea-towels [and possibly t-shirts/shorts etc? I forget], and throw them away at the end of the holiday. Or the beach towel you use if going to a hotel.
Problem is: I rely on those for my floor cloths/dusters, so I would never just bin them.