Hi, Deanna!
There sure are many new and exciting things planned for the Walt Disney World Resort over the next several years. There has not been announcements pertaining to when these new lands and attractions will be open, and may still not be ready for an early 2017 visit. Stay tuned to the Disney Parks Blog for announcements!
There are other pros and cons to these different times of year. Both the early fall and beginning of the year have lower crowd levels - something I very much appreciate! The weather in January / February can get quite chilly, while September is still pretty warm. If you wanted to visit the Waterparks or enjoy your hotel pool, September is the much better choice.
If you are arriving mid to late September, you are able to attend Mickey's Not-So-Scary Halloween Party. Wear your favorite costumes - all your favorite Disney Characters will be in costume also! Trick-or-Treat around Magic Kingdom Park, watch the Headless Horseman ride down Main Street, U.S.A, and end the night with a special HalloWishes fireworks display over Cinderella Castle.
Starting later in September is the Epcot International Food & Wine Festival which is one of my favorite events! Enjoy amazing food and beverages from around the world and enjoy fantastic music.
Have a magical day, Deanna!
~Rachel