I usually take more than one project. I take a project that is 1/2-3/4 completed and finish that one first. That way I don't go home feeling like I didn't really accomplish anything! I also take a new project that I have already cut and studied the directions so I know what I am doing (the cat fancy quilt I posted on here was a project at the retreat I just came home from). I also take two or three hand sewing projects just in case I get tired of using the machine, get both my projects finished early, or, heaven forbid, my machine breaks down! I went to one retreat where a person's machine broke down the first day and another person forgot the cord to their machine. I felt so sorry for both of them.
I hope you have a great time on your retreat and be sure to tell us about it when you return!