I'm about 50 miles north of Seattle and I leave my Intex style round pool up over the winter. A key concept is to wait until pool water temperature is below 60 degrees before closing, and to open before the water temperature reaches 60 degrees in the spring. Don't let algea get any foothold.
For closing, I bring all chemical levels into balance and then vacuum to waste until the water has dropped to the level of the dedicated vacuum fitting. I then raise chlorine to SLAM level.
I disconnect and drain the pump, and all plumbing, for storage in the shed.
The water is thus drained to the level of the lowest fitting in the pool, which leaves it about two thirds full. Rain and snow drain by themselves through that lower fitting. The skimmer drains from the bottom by virtue of the now disconnected plumbing.
I remove the six way valve from the sand filter and loosen the bottom drain plug to allow the sand filter to drain completely. I cover the drained filter with a plastic bag to keep the lazy bugs out and then place a plastic garbage can turned upside down over the whole thing and top with a heavy brick to keep it in place.
I used to cover the pool as well, to keep out the fir needles, but storms took all of our trees down in the back yard so now there is very little that falls into the pool.
This last winter I left the pool uncovered all winter and suffered no ill effects. Had no problems with algea due to low overall temperatures and the ocassional addition of bleach poured slowly as I walked around the pool perimiter. Ocassional in this case was three times as I recall.
Over the course of the winter I had to remove the occasional larger wind bourne debris and did not worry about the small stuff.
At opening the water was very clear and the bottom was covered with dirt and small organic stuff which I swept and removed as best I could before reinstalling the pump, filter, and associated plumbing. With the pump and filter working, brushing and vacuuming the pool was all that was needed before concentrating on testing and rebalancing the water chemistry.
Leaving the pool uncovered probably would not work for most people but does for me.