Another use for the pmset utility (which, like most Apple utilities, is documented: do "man pmset" in Terminal) is to tell the system to sleep when you hit the power button. In Terminal, do
sudo pmset powerbutton 1
and thereafter when you hit the power button a menu comes up with choices Restart, Sleep, Cancel, and Shut Down. I always sleep my MacBook Pro this way in order to be sure it has really gone dormant.
On the other end of the sleep cycle, I don't want the machine waking up while traveling if it gets jostled enough to shake the lid open (even briefly). The Terminal command to estabish this is
sudo pmset -a lidwake 0
For both commands, you will have to authenticate as an administrator.