The Rezzer is where you select one of many 'scenes' to enjoy. You are on a sky platform which measures 64mx64m and stays in a fixed location. The sky platform is inside a 64m square box that is transparent from the inside but not from the outside so others in the area or nearby can not easily see your objects.
It's a good idea to stand in front of the Rezzer when selecting different scenes to avoid winding up inside a wall or under a floor. Experienced SL residents know however that this is not a problem as all you need to do is move your view and select a piece of furniture to sit on. This is also one of the better ways to move around SL in general... beats walking.
**When Rezzing scenes too quickly, you may get 2 scenes stuck together. If 'Remove' doesn't fix it, it is best to leave for 2 minutes then return. It will clear itself once there are no Avatars in the area.
It's also a good idea to create your Landmark directly in front of the Rezzer, but you can create one anywhere you want that may be most advantageous to the scene you will be using most often.
Each scene is very different. The Rezzer is in a fixed location of your skybox and the scenes are built around it. Some scenes the rezzer appears somewhere inside the unit and others outside. When the rezzer is outside and you click it from a distance, you may not get a menu if there are transparent prims (tree leaves, plants, rain, falling snow) in front of it which would appear transparent to you. You cannot select something behind these objects that appear transparent. It is best to zoom your camera close in to the Rezzer before selecting.