Hi Hallie,
Well, you have the right idea of where to start....the Moms Panel! We're here to guide you through the planning process, and you'll find lots of great, tested advice here! October is a GREAT time to go, and now is the time for you to be planning.
Now I'll be honest, when planning at trip to Walt Disney World with a four year old, one thing you will probably want to choose wisely is your resort. I know for my children, swimming is a highlight of their trip, so choosing a resort with a great pool is a perfect place to start. Thankfully there are plenty of options to fit any budget. My favorite website for helping in this decision is
www.allearsnet.com Their section on accommodations is a wonderful resource! They have a user friendly library of all the resorts including fact sheets and LOTS of pictures! So I suggest you start here and choose your resort.
Once you've selected a resort you will want to research the dining options. There are restaurants for every budget and taste at Walt Disney World. Again, Allears is a wonderful resource because they have the menus for just about every dining option available. If you plan on doing a lot of table service or character dining, you might want to consider the dining plan. Unfortunately I don't have unlimited space to go into detail, but this can be a great money saving plan.
Hopefully this will help you get started. Please come back with any additional questions!