Hey , I am getting used to how to animate in Blender's NLA Editor/ Action Editor/ Dope Sheet. IN this little animation I used a walk cycle NLA clip several times as well as created new NLA clips along the way. I found a few interesting things in Blender that helped out in controlling how things went.

1. If you have the Time Scrubber in the NLA Editor on the last frame of the NLA Clip then when you go to the Action Editor the Pose is the same as the last frame of the NLA clip in the NLA editor. This is a great starting point for your creating the next NLA clip.
2. Also the Pose library is very useful. If you copy the each main Poses of your Walk Cycle without the Root Location to the Pose Library you can then create a new walk cycle anywhere in the scene by just picking the Pose from the Library. This solves a couple problems I was having. Here is a simple animation.

Little Animation