I like the way Clip Studio Paint does pan/zoom/rotate view.
pan – Spacebar + drag
zoom – Spacebar + Ctrl + click or drag
rotate – Spacebar+Shift or Spacebar+Alt + drag
When you release the modifier keys, you automatically go back to the tool you were using. It really helps not take you out of the flow of drawing with your current tool.
PaintTool SAI also does the same thing.
I think Photoshop does this too except the rotate part.