Kristen,
I've never aspired to do the Goofy Challenge (running the Half and the Whole in the same weekend on consecutive days). I enjoyed training and running for the halves - not that I'm a running nut (5'-11" and 225 lbs back in those days) but I just enjoyed the challenge. But training for the wholes (twice the distance) were MUCH more effort (more than twice) IMO. I've only run two wholes (the Disney years ago in early January and then a local marathon a month later in early February). I was sick and tired of the extra training required. But hey, that's just me. Of course, now I'm up to 250 lbs.
I was fortunate to get in with a good local group of runners (I worked with one and he got me interested) because you need a good support group for something like this.
Now I am training again for a half in April using the Jeff Galloway method. Basically, Jeff advocates a "run-walk-run" method. Based on your training and preparation, you would run for a set period of time (from one to several minutes) then walk for a brief period (up to a minute or two). Start the cycle at the beginning of the race and follow it till the end. He maintains that the net time of run-walk would be as good or better than if you tried to run the entire way (albeit at a slower speed) and your body recovers faster as a result. I'm not into times so much anymore. I just want to finish the half, stay ahead of the balloon lady, and have a good time. The line of Timex Ironman Triatholon watches has an interval setting (my 100 lap TIT does) that you can program to "beep" the run-walk intervals and repeat.
Most marathon training programs (and I didn't look at the Higdon but I think I know it) follow one of two tracks. One track is "hey just finish". That has long runs once every week (on a weekend day) and increasing that long run distance every week mostly (3 months out the long run might be 10 miles and you increase it each week to get up to say 18-22 miles) then you taper back about two weeks before the marathon. During weekdays you run short distance 2-3 days to keep the fitness level up and not lose any ground but the long runs is where you build endurance.
The second track is for folks focused on finishing a specific time so the training program builds in various "speed training" work where you build in sprints of varying lengths and hill/climbing work along with the long runs (the long runs are normally run at a pace slower than your race pace BTW). So it depends on what your goal is which method/track you use.
I have a couple funny stories from my Disney races that I won't bore you with. I would, though, suggest you run with a fanny pack and a cheap disposable camera to take pictures along the way. The first Disney half I did every 2-3 miles there was a costumed Disney character like at the meet-and-greets in the park (Snow White was definitely cute) and lots of folks stop running to get their picture made with the character. Sure it cuts into your time but hey - it's Disney. I don't know if your race would have characters interspersed along the way but I bet they will.
John VN's Coast-to-Coast challenge sounds like the ultimate. Maybe someday.......
Nah.......
I predict I have at least one Disney half left in me. They have these other races at other times of the year now (when I did it all they had was the January races) so it might work out.
Good luck to you. Wear your medal proudly after your race. I was surprised by the people wearing their half- and whole- medals when we went to dinner. We didn't know each other but we congratulated each other sharing a common bond (then got the biggest steak and baked tater on the menu with sour cream and a dessert). All over the property people had them on that night. Initially I didn't and when we went to the bus stop at the Fort to go to dinner I saw several folks with their so I went back to the cabin and got mine on. Glad I did.
Oh well. I've blathered on long enough.
Good luck!
Bama ED