I use clear leaf bags for my storage of things that I want to keep. The rule in our house... clear is a keeper... I don't trust my DH to open opaques bags to check them!
When my daughter went away to school, we put sweaters and a puffy warm coat in a bag. I lay on it to get the air out and she put the twist tie on. THEN they fit in the suitcase with lots of room besides!