you're right that in the industry people generally don't use final gather or global illumination. the reason for this is that it takes too long to render each frame. also final gather is better for still frames. I think if you are working on portfolio stuff it is a must.
i wouldn't use global illumination but i would use final gather and an ambient occlusion.

You should also look at your HDRI tutorial. they are used for reflections not lighting generally, but can be used to light stuff (IBL) you just have less control over the lights.

this site will explain everything about IBL/HDRI and has some you can download.
The Ufizzi probe might be a good one for you and its a classic!

one last thing... how are the shutters connected to the wall. just something i noticed.