I take a sheet of aluminum foil for my celery and wrap it up completely with a double fold down the long seam and again at each short end. It definitely helps the celery to last must longer.
I have used the Myers green bags, but you have to remember to not mix them up--say bananas versus onions or cheese or whatever and my house mate kept mixing them up so I gave up on them.
I love my food saver and fresh saver for most everything else. Much less "science projects" in the fridge and no freezer burn in the freezer compartment. Great investment, one of my best QVC purchases.