I use ordinary zip-lock bags for smaller items. We tend to stock up on zip-locks when we're in Florida as they're much easier to find than at home (and are sturdier) and they cost just a couple of $ for about 10, depending on size.
Admittedly, I'd stand no chance of getting a couple of beach towels in these bags, even the larger sizes, but I've found them great for keeping underwear together for different members of the family - having two teenage daughters, and because we don't take a case each, I find it impossible to keep track of ownership of undies!
I put each person's underwear in separate bags and then just chuck the full bags in the hotel drawers on arrival. I also use them for items that might leak.
I kneel on the bags to get the air out, and then zip 'em up!
I did read a tip on another board a few years ago which sounded mega-organised, but quite tempting. For young children (i.e. small clothes items!), pack a complete outfit in a bag with a tee-shirt, shorts, socks, pants, even hair ribbons, etc., then the child just picks a bag for the day and everything's ready without rummaging through suitcases/drawers.
I confess to being obsessive enough to wishing my DDs had been young enough for me to get away with this at the time!
Fortunately for them, they weren't
