Answer: To suggest an overall landscape plan is beyond the scope of a Q&A format but in general you might want to think of using the round area as an island bed for shrubs and perennials, or a small tree with a shaded bench and groundcover beneath it, or perhaps an ornamental water garden, or as a neatly fenced vegetable or cutting garden or herb garden, or if you have small children, a mulched play area for them. Or you could sod the area to return it to lawn and begin to integrate other features elsewhere in your landscape. (If you plant there, be sure to loosen the soil to about a foot deep prior to planting as it will have been severely compacted by the pool.)
You might want to have a landscape architect or designer consult on site with you to get ideas as to what could be done with your yard. Some will do this for an hourly fee while others will insist on doing a complete formal plan. I hope this gives you some ideas.
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