IT depends on where it's being held. My quilt guild is planning one for May that will be at a quilting retreat house in Crestwood KY. There are actually two homes on the site for quilting retreats. There are huge cutting boards, ironing boards, wall and everything you need except your own personal items. It has a large kitchen for cooking and all linens are supplied. From the calendar, it stays pretty well booked too. What a great idea!
One thing I have learned is to not take all the fabric with me. If I possibly can, I try to get everything cut out before going. That way, you waste less time cutting and get more actually accomplished, or at least I feel like I do. Secondly, there's less weight to haul if you have your project cut out. I do take a little extra to cover mistakes I might make.
Definitely snacks to share. Sometimes there are not drink machines available, so I usually take bottle water or tea with me too.
Most importantly, have a good time!!