How can I label both coordinates in mmQGIS? Everything I try leads to only one of the 2 coordinates (lat or lon) to be labeled. I cannot get both labeled at the same time.
You don't need MMQGIS for this. If you are using QGIS 1.8 then go to the advanced labeling options (Layer->Labeling)/ In QGIS 1.9 it will be in the layer Properties labeling tab. Click the button with three dots next to the drop-down menu for "Label this layer with" (In QGIS 1.9 the button is labeled 'E...'). This opens an expression based label window. Now type the following in the Expression box:
Alternatively you could make a field that contains both coordinates and then continue with MMQGIS.