Another writing activity my students liked was "Complete the line". I would give them a sheet of writing paper that had a space for an illustrations at the top and lines at the bottom. The illustration section would have a squiggly line in it. The student would have to use the line to create a picture and then write a story about it.
Keeping kids interested to write at the writing stations was always a hard thing for me. Our school used the Lucy Caulkins writing curriculum which focused on the students writing about things they had done. When it came to for the writing station this was the last thing they wanted to do. One of my favorites and a great writing station for some of your GT students I called "What is it?" I would find an item around my house that hopefully none of my students had seen before. I would put it in a paper bag to keep the kids from seeing it. When it was their day at this station they would pull the item out and write about it. They would try to guess what the item was and what it was used for. This could be a serious guess or something fun.