Backdrop Mountains and City of Oakland

Last weekend I had some spare time for my hobby so I worked on completing the backdrop painting. After the sky and clouds I begun with the mountains. Using Google Maps with the new feature similar to Google Earth I had a rough idea of the mountain contour around the area I'm modelling. I also found that many of the city building of Oakland, Ca have been rendered in 3D in Google Maps so I could take some screenshot of the city's skyline as one should see standing close to the 9th Ave Terminal Dock. Here are two screenshot I took:

And these are some photos of the mountains I painted so far:

Still not very happy with the result. I think that even if they should look quite far from the observation point they are too "uniform" and "flat". I think I should add some more color variation and texture to make them more realistic. Also, please forgive me for the mess I have in my garage. It's not that good to see.
This is a short video I took with my iPhone:

Lastly, this is a shot of the 9th Ave Terminal where I wanted to put the skyline of Oakland. I made a model using a sheet of paper. To me the buildings are too large and appear too close comparing with the mountains far in the back. I think I should shrink everything one third in order to have a more correct perspective.

Any suggestion is welcome.

See you soon...