I've been working on my build for 6 years, and I've had my wiring diagram made for some time now. I've finally begun assembling my harnesses and measuring wire runs. It's been a blast. For me, the big thing was hitting a dry spell where I was burned out on building airframe parts, but what has brought me back is all the avionics work and planning and integration. So far, its been my favorite part!
Feel free to scrutinize my wiring diagram, or check out my build site.