Im just curious, does anyone know what region the engine temperature should be for the 550i?

On an iron block engine normal operating temp is about 180 - 190 degrees and can go as high as 230-240 before overheating. I think the higher range is the normal op temp for BMW engines due to them being made from aluminum and having more sensors to control the temperature

probably about 220-230 F.

Normal coolant operating temperature is right around 200 F. Engine oil temperature should be somewhere around 250 F. One needs to keep in mind though that BMW now uses an electronically controlled thermostat so the DME can manipulate the coolant temperature based on different driving scenarios to help acheive better fuel efficency and engine performance. For instance while driving at slower speeds the DME may cause the engine to run hotter for better fuel economy but run cooler at higher speeds for better performance.