It sounds like ( from your second post) your cup runneth over with the "No one else wants them" fabrics. A couple of suggestions . If you think the double knits are of use because of the warmth , and they do wash and in particular dry very easliy.... some one bring a machine and machine tack instead of tying. Machine tacking goes faster than tying!
As for the excess of less than desirables , it may be time to share the "wealth" with another charity .... GoodWill. That way a very good charity get what ever value or use that maybe in the fabrics ... to use for charible works. You may be able to get notificationfrom Goodwill when items that you can use come in .. such as batting! I have found batting at Good will on more than one occasion.
I would approach the issue that while your group has a "wealth" other orgaizations are suffering in this economy. Figure out how many quilts are your annual goal , and estimate how many "quilts worth" are in the stash ... come to a number of years worth is reasonable to store considering more fabrics will continue to arrive.