Off the top of my head, and in no specific order, going from AC10 to AC14 will gift you with;
-Teamwork 2.0 (very big for you you specifically)
-Virtual Trace (Big one!!!)
-Multi-core aware (faster section and elevation window generation)
-64-Bit capable (but not on Mac ....yet)
-Improved Curtain Wall tool
-Vastly improved 2D window line quality display
-Complete Complex profile functionality (truly curved paths)
-Considerably improved OpenGL display quality in the 3D Window with shadows in AC14
-Improved Library parts for certain objects
-View alignment to non-orthogonal axis in plan window
-Improved Schedules performance and regeneration.
-3D Documentation (dimensioning and annotation of 3D views)
There are probably others that I might not be thinking of right now and others may chip in, however the bottom-line is if you want a big and good reason to upgrade which even you're bosses will agree to, simply put;
you will be like 2-4 times more productive, (if not more) if you choose to upgrade from 10 to 14 (latest hotfix - very important!).
The biggest selling point for you (to sell to your bosses) really should be Teamwork 2.0 which is vastly improved over what you have right now, and considering the fact that you point out that you use Teamwork a lot.
Hope this helps.