A big congrats on your upcoming marathon Joel! Wilderness Lodge is the perfect spot to get your training runs in! I would stay away from the main, external roads wherever possible - drivers on Disney property can be distracted and don't expect to see pedestrians.
There's a one and a half mile path that goes between Wilderness Lodge and
Fort Wilderness campground. Click
here for more information on the trail. Fort Wilderness is huge, covering 750 acres. I recommend running to Fort Wilderness and then running through the campground. There are so many roads throughout that you will easily get your distance in, and the setting is gorgeous and relaxing. There will be so much to see running through the campsites - you'll be amazed at how many are decorated!
Your resort also has the Sturdy Branches Health Club free for your use, so you can always use the treadmills there as well.
Be sure to check out the
runDisney website. Here you'll see the huge variety of races at both Walt Disney World and Disneyland. You'll find everything from family fun runs to five and ten k races, half and full marathons! You can't beat the setting and the medals are the best I've ever received in any of my races!
Have a great run Joel!