Hi Tom, there isn't anything for automatically rotating just around the selection - it would be easy especially when working on things like solids for the rotation point to be off screen which makes for some weird behavior.

The 3D rotation happens around a rotation pivot point that's always located on a line going down the center of the 3D view. The main ways for setting the rotation pivot are either the "Reset" button or the "Zoom area" button both of which are on the bottom viewport toolbar.

Reset will fit either the selected objects or on a second click everything to the visible screen, and it also sets the rotation pivot point to the bounding box center at that time as well.

Zoom area lets you zoom in on a specific target window, and the center point that you pick for the window will become the new pivot point.

- Michael