noticed that your decking reinforcement is basically laying on the subgrade rendering it useless and subject to oxidation and eventual deterioration. It should have been lifted a couple of inches for proper encasement and functionality. (Midway, 4 inch deck = 2 inch lift to run welded wire right through the middle of the deck) Just like the rebar for the gunite is set about three inches above subgrade for its proper encasement by the gunite. That being siad, I think your backyard is a mini paradise! Great concepts and as most everyone else has said, I too like the curved beam for the spa!