#skycity I would suggest that the bottom level should be water based – perhaps 2/3 available as a swimming pool, with the walls of the swimming pool being mostly clear glass with fish being on the other side of the glass (or plexiglass) – meaning that the glass need not be full structural strength, just strong enough not to get broken by contact. The absence of wind would mean a very light plastic dome canopy could contain the highly humid atmosphere).
At the other levels, I would devote at least 50% of the area to nature – growing plants that can live in low light conditions, and alternating levels between active and passive recreational uses (active games verses just sitting or strolling or playing chess).
Perhaps a couple of levels devoted to public meetings and discussions – perhaps under acoustic dampening domes .
One could use flowing water in recirculating systems to add variety, without the need for much depth creating excessive strain on the structure.