my tank is almost the same foot print as your new tank 48x30 and i use two jebao MCP-180 (wifi sync) at top of the tank and two SOW-20 at bottom back corner to move the water at bottom. not recommend this if you are not doing BB.
I'm probably going with sand. Tropic Eden Mesoflakes are my go-to flavor at the moment. Just enough to stay put in my current system with pumps going full blast.
I probably also won't have SPS throughout the whole tank. I'll have one island dedicated to SPS, but another dedicated to my Magnifica and BTA's. Sand to separate them will be key. So most of my SPS flow will probably only be in one half (give or take) of the tank.