Nice shots!
I think #1 will come good with some exposure compensation (lighter)
Also, #1 and #4 appear flat because the DOF is infinity - #1 would pop if the crowd was slightly out of focus.
I think #2 and #3 would stand out even more, with some levels / curves adjustments, boost the colours and a sharpen. e.g the red car in #3.
Edit - I hope you don't mind I had a little play. All I did was boost the saturation and sharpen in Picasa2. It surprised me how much sat this image took, I boosted by about 80%. Perhaps you need to review your in-camera settings for saturation.

I boosted the shadows here, to create more contrast. I'd probably crop a bit of sky out of this as well, if I needed the shot.
