I've only done online quilt-alongs and they're really fun. I like the idea of a retreat though. I've been to Paducah several times with a bunch of friends and we had a blast- not quilting, but eating, talking, shopping, and most of all, laughing. Not a retreat but a great time with quilting friends.
I don't belong to a guild. The one in Columbus is way too big for me, so I don't really know who has retreats. If I did I would probably enjoy one.
We used to have a local quilting group and I really miss it. We met every month and took turns hosting. There were maybe 15 of us. That was so much fun!