Thanks for feedback!
Pool is located in wide-open backyard with southern exposure so it gets lots of sun all day being in zone 9 on the East coast just a couple of blocks from the marsh. There is a saltwater pond, good for fishing, just yards from the pool site. And there's a small existing greenhouse which will work tacked onto the back of a shed.
Because of those elements already in place and because the yard isn't real big, we've decided the best use of the old pool for us is as a garden spot. We hope to plant the back yard pretty full with fruit trees, berry bushes, perennials, etc.
I had looked at the greenhouse site and other sites involving water ideas but with the existing pond which is great (rises and falls with the tide), felt those ideas weren't the best choices for our situation.
What we plan on doing is creating a big compost pile in the pool using yard waste folks put out for pick-up on a weekly basis, probably adding fill dirt and sand as we go along.
My main concern is that we may create problems doing this. Certainly this would be a compost pile too large to turn.
Again, all suggestions appreciated.