Hi Karen!
Thank you for bringing your question to the Disney Parks Moms Panel. That's a great idea to give Mommy's little cheerleaders the best view possible as she dominates the
Disney Princess Half Marathon!
Though the Disney Princess Half Marathon course will not be officially released until a few weeks prior, I think your best bet would be to use the past courses as a point of reference. While this is subject to change and not a guarantee, it's the best bet you'll have for planning farther in advance. For the Half Marathon course distance, the only Walt Disney World Resort hotel that the course has been close to in the past is
Disney's Contemporary Resort or
Bay Lake Tower. They will not be able to see you from the balcony, but it will be a short walk to get to a point where they can cheer you on. This will also give them easy access to get into the Magic Kingdom to cheer you on from Main Street U.S.A.
Depending on what your pace is, another option is to stay at one of the resorts near the BoardWalk, where they can enter through the International Gateway once Epcot opens to the public and cheer you on closer to the finish. If you think you'll finish before the park opens though, this may not be beneficial. These Resorts would include Disney's BoardWalk Inn & Villas, Disney's Beach Club Resort and Disney's Yacht Club Resort. If you stay at one of these, you'll also catch a good view of the Disney Princess Enchanted 10K runners, if the course is the same as years past.
I'd recommend searching for
Disney Princess Half Event Guide from years past to give you an idea. Please let me know if you have any other questions!
-Lindsey ºOº