Retina MacBook Pro - Quad core vs. Dual core and virtual machines (VMware Fusion)
Solution 1:
I would say that will depend on your work. If performance is of the essence, go with the 15" model. You're also going to appreciate the extra screen estate when having documentation and your code side by side.
Graphics however, play little role when it comes to virtualization especially when you don't run any graphics-intensive apps.