This may be an old thread, but for anyone who's interested, a couple of things my chapter does is have Brotherhood Night once a week that's officially designated to doing different things together as a chapter and the events are scheduled well in advance.
We also go away on retreat weekend once a semester, the entire active chapter.
The second one certainly made for an interesting weekend when I was living here as a pledge this semester and woke up to find the house empty all day.
It wasn't until it was almost midnight that I remembered, "Oh yeah that's right.. they went on retreat this weekend."