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Initially, we were debating between two versions of the panel called either "Layers" or "Data Sets." While user feedback was split, we decided to go with "Data Sets" for future iterations. 
Overlay/Intersect: We added this button to give the user more ways to find relationships between data sets.
We tried several different ways of having the user add new WiFi towers to the map. We initially had an "Add Towers" button that would automatically add some number of WiFi towers to the map. When we had the button directly beneath the list of layers, it was confusing for users because the task of adding towers was not logically connected to filtering layer views. We moved the button to the bottom in the next iteration.
Overlay/Intersect: We added this button to give the user more ways to find relationships between data sets.
To deal with the confusion over adding towers, we We later decided to have an "Options" panel that would appear beneath the data sets, to make the application more flexible. We tried to have the user click on the data sets to access its options, but this was not immediately obvious and took the user a while to figure out. After the user testing, we realized we should have a small options icon next to each data set.
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