Regardless of what you get, make sure you run TLP (it's a daemon that out-of-the-box will enable lots of power-saving tunables when unplugged, and disable them when plugged in). It can have a significant impact on battery life.
Does anybody know if running TLP has any specific advantages over running powertop?
Will powertop automatically apply changes based on the state of the machine? I always thought of TLP as a daemon to do things automagically and powertop as more of a diagnostic tool. (e.g. on my machine with the power unplugged, powertop shows all green on the tunables tab).