We use a rotary dryer. Works great for us because we don't really have the room to put up enough traditional line to hang a whole load. I put it up when I have a load to dry, and take it down to store in the shed when I'm not using it. I can fit about two loads on it at a time, so I have plenty of room.
Mine is the square umbrella-ish kind. I like it because I can basically stand in one spot almost to hang stuff out. The only thing I don't like is how close the individual lines are - but I only use every other one.
And I use both the spring and the other type of pins...they're useful for a variety of applications.
I have two 4x4 posts at each end...they are about 4 feet apart....then 20' from one end to that other. Then we have a trellis all the way up on one side with a clematis on it....the other end only has a tressel a couple feet high with nothing on it, just blacked eyed susans in front of it. Then we have a 2x4 going acrossed from each 4x4 that is like 5' or so long. Then we have 5 rows of clothes line strung throw that. We do a TON of laundry so we need a massive amount of clothes line. It is big enough to hold two loads of landry from our front load washer.