I'm very new to texturing in Blender. When baking the normal map of my model, it is unable to render correctly because my model has too many varied spacing lengths between geometry to have a "ray distance" setting that bakes cleanly. Is there a way for me to bake the model in chunks, so that I can avoid this problem? If I have to go as far as breaking my model into smaller objects, how should I go about piecing the resulting renders into a single normal map?
If you uncheck Clear Image checkbox in the Bake/Output you will be able to bake from different chunks sequently to the same image. You may want to lower the Margin distance so that the margin wont overwrite previous bakes.
Another way of dealing with this type of problems is to (copy and) move different parts together with their high-poly counterparts so they will be baked all at ones but without intersecting with each other.
Or, as previous suggested, create a cage mesh so you can control the ray length in detail.