I have a tilt-wheel mouse, and set up clicking the wheel as Copy, and right-tilt as Enter - useful in Excel. I rarely use the Copy button on the mouse, though, as my left hand stays on the keyboard and can hit Ctrl-C easily. But with the left-tilt as the Back command and the right-tilt as Enter, I can leave my right hand on the mouse for the majority of the time.

Incidentally, as an AutoCAD user from ages past (when there was no ACAD for Windows), I learned the indispensible process of assigning aliases for frequently used commands: I use CC for Copy, MM for Mirror, AA for Array, etc. Never needed one for Erase - I got so I can type in the entire word and tap the spacebar in less time than most people take to click the mouse.