Spent a few days on this so it's not that polished but I wanted to try some further testing with 3D tracking and Camera mapping. Tracked and undistorted the shot in SynthEyes then brought the track into Cinema 4D. I then created multiple projectionman cameras to remove the people, cars, reflections and extend the building. Also, I added a CG car in the place of the real cars. Then did a quick cloth simulation for the banner. Few coverage render cameras to fix a few projection things.
I used photoshop to make the extended building painting (spent very little time on this part). Then I used After Effects for all the color correction, lens flare and 3 Trapcode Particular emitters for the snow.
I certainly have some things to work on and/or fix to make it a final comp but I'm pretty happy with the result for about 2 days of work.