How to extrude "Up To" or "Offset From" multiple faces
Both Insert - Boss - Extrude and Insert - Cut - Extrude features allow you to use a target face as either an Up To or an Offset From end condition. But you can only select one item at a time for the target in the Extrude dialog. What if the extruded feature is going to overlie more than one face?
The solution is to use Insert - Surface - Knit. Prior to creating the extrude, use Knit to gather together all of the faces that the extrude is going to contact. This will result in a single surface object in the FeatureManager. Then, when you are in the Extrude dialog, select the resulting knit surface by clicking on it in the FeatureManager.
