I had a blanket fort between new year and Chinese new year. It was a blast. I kept it up for a week or so and camped out in my living room :-)
I encouraged folks to bring blankets, so the fort could expand as more friends arrived. They were also told to bring comfortable clothes. Everyone had a great time!
I want to set up a permanent fort in my spare bedroom. Haha, let's see how long it takes me to get around to that.