Hello Sharron,
I know you must be looking forward to your upcoming trip to
Walt Disney World. The magic is waiting and you are going to make so many fun memories during your stay.
Disney's Coronado Springs Resort is a wonderful choice. My family enjoyed our stay there several years ago when we went as a huge party of 17 with extended family and close friends.
I am happy to tell you that you are allowed to decorate your resort room window. I have seen this on many occasions, especially during the holidays. I would just recommend you clean up all decorations as you leave, so as not to add extra work for the amazing "mousekeeping" staff! In regards to the doors being metal, I am not entirely sure. While I have seen the windows decorated, I have not seen magnets on doors before, like I have on the Disney Cruise Line. So, even if they are metal, I cannot confirm that those magnetic door decorations are permitted.
I hope this helps you in your planning. Thanks for stopping by the Disney Parks Moms Panel with your question. Have a magical trip!
~Allison L