Well, things went smooth. Because I have a "flooded" system where my pump and filter are below the skimmer and return lines, all I had to do was open up the filter and pump, then open the valves for the returns and gravity drained the lines for me. The same concept worked for the skimmer, however, I would always see some water in the drain of the skimmer...almost like you would see in a sink drain (due to the trap). Would a skimmer normally be plumbed with a trap like a sink drain? I wanted to be sure it was empty, so I poured in some anti-freeze and had my wife down at the pump to let me know if she was seeing it. It wasn't until I started pouring it fast that it finally "let loose" and got down to her. So, its almost like somewhere in the plumbing (which is all under ground), there is a point where the pipe goes up hill and needs a little pressure for the liquid to drain. Or maybe its just because there was no alternate source of air for the line (rules of plumbing drains). On my returns, since I have two, if you keep them both open, they both will drain. Its a slower process if you don't open both. In any event, all lines are drained, I added some anti-freeze just in case, and all lines are plugged. Installing cover in the coming day or two (not enough hours in the day).