I'm pretty happy with this one:
And a little step by step for what it's worth:
1 - I start with a few perspective lines on a white layer. I then add another layer on top of that where I block my values (in "multiply", so that I can still see the perspective lines). When I'm done, I merge the two layers. This step took 8 minutes on this painting:
2 - I create a new layer on top of my gray scale layer in "colorize". I block the basic colors. Five more minutes:
3 - I start noodeling. At the end of this step, I'm 20 minutes into the painting.
4 - More noodeling, that's the fun part! I used two brushes on that painting: a bamboo pen modified and the happy glow brush for the lights. 40 minutes:
And more details to finish... et voila! :)
60 minutes total