Recommended Spiritual/Healing Retreat

Does anyone know of any spiritual / healing retreats that you would recommend? Preferably 3 days or a week long coming up soon? I have a sister having a hard time right now and would love to go to one for her birthday in April. 

Or what are some retreats you have already been on and what was your experience? What are the musts and must nots in your opinion?! Any experiences you would like to share that happened while being on a retreat?