I have been to a couple of weekend retreats (Fri pm to Sunday noonish) put on by a guild I belonged to at the time. They were a lot of fun. Held at a church camp building (dorm style sleeping). Everyone was asked to help with a meal and cleanup time. It was lots of fun to see other peoples projects and sometimes just the fabric combinations they come up with. I have also been to day long retreats where there is a project or class you can take. Again lots of fun and a great way to learn new tricks of the trade.
Like everyone else it would be great to do a weeklong retreat...but that thing called money gets in the way. Maybe someday in my future.