I went ahead and took the plunge and registered for the 5k as well. The chance it might be "Frozen" themed, which might make it sell out quick convinced me to just register now. I am sure my dd and I will run/walk that, so I'm not too worried about it impacting my GSC, because I was up all three days this year too. I'm more worried about what she is going to want for a costume
Turns out my sister is busy on Tuesday so I have to register her for GSC at noon so although I thought I was all done with registration, instead I will be caught up in the craziest frenzy of all. Yikes.
A word about costumes which someone brought up, I chose this past year to wear themed running clothes for the 10K and same for the half with a tutu added. For the 10k I was ariel with a green skirt, purple top and red headband with flower. For the half I wore running shorts (spandex type) under my sleeping beauty tutu and a pink tank top. I made the choice to decided early what characters I wanted my outfits inspired by, then on a every week or two basis I'd check my favorite running clothes suppliers for sale stuff that fit the bill. I got most of my stuff from Athleta, and it all worked great. The top I wore for the half is my favorite still. I didn't want to have to worry about a costume making me hot, having chafing issues, or any other annoyances. While there were many more much more elaborate costumes people looked awesome in (hello lady brave enough to pull off slave Princess Leia) I felt like I struck a nice balance of comfort, running function, and being part of the costume atmosphere. It turned out to be very warm and super humid, so I am glad I was comfortable.
With 3 races this year, I am not sure what I want to do yet. I did see that Athleta tank in a perfect Cinderella blue and picked it up so thats a start

Other than that I'd like one costume to be non-princess.