So, this project is really in the beginning stages.  I am focused on the exterior of Hogwarts Castle and had to place another order as I am out of lights, so waiting to continue work.  I also don't currently have enough connectors to light up everything that is currently on the castle, but what you see if the main portion of it.  The castle has 2 large hall areas and I placed 2 cool white PICO leds in each area to illuminate the stained glass.  

The PICOs that I used were ones that I soldered myself.  Mainly do that because I have experience soldering small items and really enjoy it.  To create the lights along the path, I used spare black studs so that I didn't alter the sets existing lego pieces in any way.  I used a 5/64 drill bit to put a hole in the spare stud.  The light then goes between the existing black stud and the drilled spare.  This enables the light to shine through the drilled hole and illuminate the yellow stud that comes with the set.  

Future plans: 

- Illuminate all lights on the exterior of the castle (to include the boathouse).

- Build a water scene leading up to the castle in which the lights on each of the boats are also illuminated.  

- Figure out a way to neatly conceal the wires from view.

- Perhaps incorporate some other good ideas that any of you on this forum might have.  I am a newbie when it comes to this hobby.

Thanks for checking it out and I look forward to hearing what all of you have to say!!!!