Balancing Audio to -12db without using Audio Meters????

I am working with a few songs and some are louder than others. I want to be able to balance out the audio so they are all at around -12db.

Is there a quick way to do this in Premiere Pro CS 6?

Right now I am clicking on the audio clip, then going selecting "Audio Gain." A box comes up and it has 4 choices:

1) Set Gain

2) Adjust Gain

3) Normalize Peak

4) Normalize All Peaks.

Which one should I pick?

Is there another way of accomplishing what I want to accomplish inside Premiere Pro? If so, How?

Thanks in advance.

Premiere Pro CS 6

Power Mac Xeon

10 GB RAM