Hi Shannon!
The Princess Half Marathon is such a great race! I usually bring my family too, and we make a fantastic vacation out of it.
If you stay at one of the Disney host resorts, it will provide free bus transportation to and from ALL weekend race events. (packet pick-up, expo, kids races, 5K, half marathon) This is absolutely the most convenient way to go. You can always grab a cab or drive yourself to the starting line, but because of road closures and traffic, that can be very difficult. I have done it both ways and when I drive myself (with a rental car), I usually leave at least three hours prior to race start time. If possible, definitely stay at a host resort.
The host resorts are different for each race. They haven't been posted yet for the Princess, but you will be able to find them on the
Princess Half Marathon website once they are finalized. You can also call 407-WDW-IRUN to get more information about the resorts, resort rates, and package availability.
I hope this helps! Please let me know if I can help you with any other questions as you prepare for your race!