As of Looker 3.50, we have several new features for interactive maps.
Region Data & Map Layers
You can now use built-in or custom map layers on the interactive map by using the map_layer property in LookML. You can also use several built-in map layers and the U.S. zip code layer is automatically used if you are using a zip code dimension. See this article for more information.
You can specify the opacity of the colors used in the heatmap for an interactive map.
For an interactive map visualization, click the Edit button and choose Plot. In Heatmap Opacity, type a number between 0 and 1, such as 0.3 or 0.8.
This example has a low opacity setting so the colors are muted.
This example has a higher opacity setting so the colors are stronger and obscure the underlying map more.
Map Labels Above or Below Heatmap
You can choose to have the map’s labels drawn under or over the heatmap. For an interactive map visualization, click the Edit button and choose Map. On that menu, enable Draw Map Labels Above Data. To use this feature, the custom map must be defined with a labels-only option.
This example shows the underlying map’s labels under the heatmap:
This example shows the underlying map’s labels over the heatmap, making the labels very clear: