I had a huge pile of double knits when my sweet MIL passed away..
I made stacks of lap robes for the rehab facility she was in for a long time.. They love the quilts and they stand up to their constant washing and drying.. Those things never wear out!
I made a large, tied, double knit quilt for each one of the cars.. the quilt lives in the trunk and is perfect for a spontainous picnic, or should some one have a flat tire, or worse, it can be spread on the ground without worry to protect good clothes.. You know, those break downs never happen when you're dressed for crawling under the car! Both of our cars have one, and each of the kids cars have one.
I cut some yardage into strips and made braided rugs... They work up wonderfully and you don't have to worry about the raw edges fraying.. so they stay nice.. and can be tossed into the washer and dryer..
I made a bunch of simple mats for our animal shelter. Those poor animals have nothing but concrete or wire to rest on if someone doesn't make washable mats.. The animals don't care if your stitching isn't perfect or if the knit is an ugly one.. They are more comfortable and I'm more comfortable thinking they are resting easier.
I've made a stack of simple totes to take grocery shopping with me.. I also use those for hauling all sorts of stuff, like library books, or flower pots.. things that are heavy or dirty and I need to carry a bunch of them at a time.
I made a firewood carrier to help bring the wood into the house.. I can load as many pieces as I can carry and the fabric is stronger than I am.. and when it's dirty, into the washer it goes.
I made a teepee for one of the grand kids...
We have set up a small tent city in the back yard during the summer.. I didn't do anything for that but bring out the fabic.. you can't hurt it.. once the city came down, I washed the stuff up and it went back to the sewing room no worse for the fun.
My personal favorite is the rugs.. I love those rugs..
I don't wear it anymore.. but I love it for a simple quilt made of lots of colors.. The one I have has smaller squares on one side and large squares on the other.. no batting. . tied with black yarn.. It's warm and will probably wear forever.
Whatever you do don't throw it away just because you don't wear it anymore.. and with the price of cotton fabric going so high, who knows, polyester may make a comeback!! It's cheaper to keep it and use it a bit at a time, than to toss it and wish you had it back!