Winterizing: blow-out vs antifreeze for longer term storage?

I would first drain everything, then fill lines with antifreeze to make sure. I would then drain again, and blowout all lines. Leave antifreeze in P-traps, and enough in tanks to protect the tank drains and valves. I would not leave antifreeze in the lines, water heater or fresh water system for that long. Simpler might be OK, but for long-term, do everything you can.