Cool, thanks everyone.
FWIW, I'm not worried about moths--I've never gotten them in sugar, though I have in spices/flour/pasta and dried flowers, ick. I just thought since I have room in our extra freezer that it could be a good storage spot. I also don't have a good pantry--all my stored food is on an open baker's rack and the kids are beginning to play "shopping" and drag things around the house, which is OK for a can of beans, but not cool for a sack of sugar! It also makes the freezer more efficient to be full, so that can't hurt either.