I agree with the creams, browns and more neutrals. Maybe a log cabin with a little green in the center block and brown on one side of the log cabin and different creams on the other side. My opinion on a star block is that it would be too defining-especially with the floral drapes. Also, think if you went to Jenny Doan and looked at her tutorials you may find something you like. Another thought is to google "brown, green,and cream quilts" and visually see if something looks good to you. Anything you make will be a treasure to your sister so don't worry too much-just enjoy making the quilt.