Glad to hear you received and like one type of yarn storage. I hope you can get the cats locked out so it works properly.
As for the vacuum storage bags (space bags?), I would think they would be really REALLY unhandy. I go through my stash about three or four times a month. If I had to drag out the vacuum cleaner and "re-suck" those puppies flat every time, I just might scream. Nyah, I probably just wouldn't do it!
Under the bed storage (maybe in conjunction with Ziplock bags), sounds like a better idea to me. Hope you've got a big bed!