To be honest, I would just stick with the top end model and not upgrade anything. You really won't make use of the extra power.
However, if you upgrade anything, the SSD would be the way to go, but I'd really forget the rest. The extra graphics memory won't make any difference for any application to be honest (you'll run out of GPU power far before you run out of graphics memory), and you don't need extra memory to run multiple monitors, in reality. i7 will give you HyperThreading and a tad more performance, but for music and gaming there again won't really be any difference.