I've been using packing cubes--Eagle Creek and otherwise--for years.  Yes, you could use ziploc bags, but if you can invest in some of these you'll thank yourself every time you travel.  Not only do they make it easier to pack and unpack, but they serve as portable 'drawers' in your hotel room, and will presumably cut down on TSA rummaging if your bag is searched.  I use them at home, also. I have them in all sizes and several colors.  The black-and-white ones I gave to my daughter this year because she has mine and I want them back!  They are different from my older ones in that the top is not mesh all the way across, and I think the fabric is a lighter weight, but so it goes.  There are other mesh packing cubes out there, but EC is my favorite.