Hi Jodie!
You can ride the same buses that the runners use to get to the start area. Do be aware that there will be a period of time, up to two hours around when the race begins, that buses will stop running. The schedule will be available to you before race day.
My favorite place to spectate is in the Magic Kingdom! Watching the runners come up Main Street USA is so exciting! The monorails will be running from the Epcot parking area (where the start is), or if you are staying at a monorail resort, you could take them to the Magic Kingdom from there. The runners will be coming through the Magic Kingdom around mile 5, so it will be before the park opens, and therefore, no admission is required. Anyone can join in! (I do recommend allowing at least one hour travel time to the Magic Kingdom from the Epcot parking lot. It shouldn't take this long, but when I was a spectator in 2012, our monorail got stuck for 30 minutes)
If you go to the
Walt Disney World Marathon website and click on the SPECTATOR tab, there will be more information for you. I am hesitant to recommend park viewings until this year's course is finalized. Viewing areas and mile particulars will be on the SPECTATOR information page once the course is released.
Be sure and sign up for Runner Tracking. You'll find this link on the website closer to race weekend. You can sign up to get alerts when he crosses certain points of the race, and will help you be aware of where he is on the course.
Be sure and let him know ahead of time where you plan to stand. This way he can also be looking for you. Seeing a loved one on the course can be a huge boost to runners! Please let me know if you have any other questions, and tell your husband good luck!!