Well I can do decent designs, but what Kainzo picked me up for was Redstone ( I was sorta well known in the official minecraft forum for the summer in answering redstone questions and showing off big projects).
If you can do something that will impress Kainzo, then you are a step ahead in convincing him that you are valuable to the architect team. Look back at some of the previous architect applications, each of us are unique and have a style that we are comfortable with. Beside towers, a lot of the team have their own ideas rather then base it on something already made in real life or on the web like dragons seems to be popular, create something stunning and appealing to the masses.
I don't have any ideas on a build for you since I deal with redstone mainly, look around for inspiration and learn off that. Similar to your situation, I learned off by watching others and once I learn each circuit's function I can easily combine them together to perform functions and tasks like I do in programming. A puzzle where each piece can fit in different patterns but I have a nack in making the build small and perform the function faster/better then most other designs.
Architect may not be for everyone, just saying "Beauty is in the eye of the beholder".
I think this is cool since I built it but not everyone will agree.