Not sure what the differences are between 2011 & 2012 premium package. 2012 135 had electric seats standard, and premium added leather, auto-dim mirrors, ambiance, and bluetooth.
The auto-dim and leather are pretty important features for me. If electric seats/memory are premium for 2011, then it might be important if you are going to share driving.
The rest of the stuff, I could take or leave. Well, except for the garage door opener, that is pretty handy.