Susie, usually the cruises have a price for double occupancy, and and additional price if you want single occupancy. Also the cruise I looked at has set class times, and then you can spend the rest of the time doing what you want, including stoips at ports. I think the classroom is open to sew in if you want after the class times.
nhweaver, the cruises I've looked at provide the machines so you don't have to take yours. The retreat I looked at, you bring your own machine. I've never flown with a sewing machine before, but I would be driving if I go on the retreat.
It looks like I'll be going on the Moda cruise in January- I think I've talked my mom into going. She's freaked out by the idea of being on a boat, but I think I can drug her to get her on, and once she's on she'll be ok
We'll definitely have an inside cabin so no windows.