##RAM upgrade above 8GB if...##

 - you do run Virtual Machines excessively because you need to allocate a lot of RAM to the virtual OS
 - Other than that, this will most likely not be necessary. Mac OS X operates very efficient with 8GB of RAM. If you do not run VMs, there will  be *no increase in performance* in most cases!

##SSD upgrade if...##

 - you want a snappier response throughout the system.
 - you run big programs such as Adobe or photo editing software that take long to load.
 - you need faster boot/shut down/sleep times.
 - if you carry your MBP around a lot. SSDs are very shock resistent. No mechanical parts move.
 - if you want a more quiet MBP.

SSDs also consume less power. But you won't notice it significantly.

Think of this:
In today's computers, the bottle-neck of processing is usually the hard drive. Processors generally need to wait for the hard drive's read/write operations which are a lot slower. Thus a faster hard drive is needed for a better overall performance in processing. RAM won't help if the needed amount is saturated.