I’m sure it’s a stupid newbie question, but I see no apparent rotation tools in Layout. I’m looking at a non-perspective top view of my model. I need to rotate the view 90 degrees. What do I do? (A web search on the subject was not my friend.)
Thanks-
Well, it is a newbie question anyway. 
Select the viewport. In the center is a blue dot with a short blue line extending from it. Click on the end of that line and you can rotate the viewport.
That handle thing can be dragged to some other point in or around the viewport so you can set the center of rotation to somewhere other than the center of the viewport. That center dot is also used as a precision locating point so you can easily line up the geometry in one viewport with that in another. Drag that point to a corner in your model, for example, and then move the viewport so that point corresponds to an appropriate point in another viewport and it’ll snap there.
This center handle doodad is also used for shapes and text boxes.
Dave many, many, many thanks!