Make sure you take your power cord and foot controller. EVERY retreat I go to, someone leaves theirs at home.
Bandaids
A portable light. I purchased an ott light that is rechargeable. If I don't have enough plugs around my station, I can charge it during the day in the bedroom and have plenty of light in the evening.
Hand sewing and machine sewing in case you get bored or the power goes out
Depending on where you are staying, we always bring our favorite coffee mug and wine glass.