I like where its going so far. Here's a few things that may help out.
1. The fire flies you mentioned are most likely your material. Use must have some blurry reflections so increase the subdivs for the glossiness. You can also do it globally but it doesn't look like you need to.
2. The glass in the top and lower rails is harly existant. You can do a few things to fix them; Add some color to the fog color of the glass material such as green;Use white for both the reflection and refraction and black for the diffuse, also enable fresnel.
3. The light on the left side are alittle harsh. Lower the intensity and soften the edges.
4. If a viewer of the street saw your image, would they what they are looking at and what the space is or what it is used for? Is there anything you could add to help engage your audience more?
Hope that helps
EJ