I'm also headed to a quilt retreat in a few weeks in Texas. Went last year and am totally hooked! As far as "essentials" - I just pack everything I think I'll use from my quilting room. Besides the obvious (my machine, materials for all projects I'll be working on), I take my own cutting mats and iron with small ironing board unless I'm ironing something big. I also bring an Ott Light & a lighted magnifier in I need extra light. If I'm sewing a lot without taking many breaks, my eyes will get tired and the extra light comes in handy. Also I take lip balm and moisturizing eye drops. Oh...and house slippers. Once I get there, I'm in my house slippers pretty much the whole time. Comfortable clothing. Snacks, gum, camera or your phone camera. Okay -I'm getting very excited to be on the road soon!
Hope you have a great time at your retreat!