OK, gswitx, Thanks very much.  Yes, I am good there.
 
Here's what I ended up doing.  I used the triangle tool to create some triangles.  They were in the wrong place and were the wrong size, but that was ok.  I used the razor to erase all but two nodes, then right-clicked on the nodes to edit the properties.  That gave me one diagonal line.  I copied it to the next measure and edited the nodes to reverse their left-right values.  I then had straight lines for left to right and right to left pan.  I just copied those over and over.
 
I still think there must be an easier way to draw a diagonal line, but this worked.
 
Thanks again for helping.

I think the line tool doesn't draw a straight line b/c that is actually the default behavior. You don't need a draw tool to get a straight line. You just add two nodes and move one of them and you get diagonal lines.

Sorry to beat this to death, but why wouldn't the Line tool draw a line?  In every other software application I've ever used with a line tool, the tool draws a line between two points, and that line can be horizontal, vertical, or diagonal.
 
The second issue is that the freehand tool will not draw a single node.  I have to draw a sloppy freehand set of nodes and then erase nodes and move nodes to get something useful.  That makes no sense when there is something called the Line tool.
 
Finally, the behavior seems erratic.  Sometimes two nodes will have smooth linear automation between them, sometimes they will have abrupt changes from one node to the other (lie an L shape instead of a diagonal), and sometimes they will be connected with a cruve..
 
What I am looking for is definitely not odd or exotic: I just want a smooth change in volume and pan from point A to point B without a lot of complicated editing.
 
So, how does one add a node at 100% Left, a node at 100 Right, and a smooth transition (diagonal line) between them?  Same question for volume.
 
Thanks.

So, once you create the envelope, you don't need to use drawing tools to do what you want.
 
I almost NEVER need drawing tools for basic volume and pan automation.
 
To set focus on a given envelope...
If the envelope doesn't have the focus, hold down shift and click on it. This is the easy way to change the focus between clip, pan envelope and volume envelope.
 
Adding a node...
Once the envelope you want is highlighted, just click on it. This adds a node. You don't need the draw tool.
 
Next, move the node you added up or down.
 
It's as easy as that!
 
When do I use draw tools on an envelope?
If I have a vocal part and I want slight variation in pan to move in time I might use the sign draw and hold down ctrl+drag to create a sign wave variation that is subtle but gently draws the listeners ear to the vocal.
 
My AlphaTrack hardware controller definitely uses the line draw method as I move the fader on the AlphaTrack to draw in automation.
 
In this video...
https://www.youtube.com/watch?v=fRU3bU5C4mg
Around 5:35, I add a couple of nodes and add some volume automation while playing back the track. I'm clicking to add nodes and ctrl+clicking to select line segments in the automation and move them up and down.

You've gone to a lot of trouble here and I don't expect you to keep responding, but something is missing here.
 
I have music in a track.  In this case a soft synth.
 
I used the track drop-downs and selected Automation | Pan.
 
Clicking with a drawing tool does not create a node.  As in Scott's video, I can use the Smart tool to highlight a section of the track and then if I click a certain way, I can get two nodes.  But then I have to edit the node properties individually and, as stated in my previous posts, that may or may not result in smooth automation between the nodes.
 
Whether or not there are better ways that I am apparently to dumb to understand here , how does one 1-draw a line with the line tool or 2-draw a single node with any tool?
 
I cannot believe this is so complicated.  Panning smoothly from one side to the other, or moving the volume up or down smoothly is a pretty basic function.

One thing that is rather annoying about X3 and automation is that I have been relying on a CS for countless years but CW has made creating automation too darn easy with the mouse.
 
Often times now I find myself forgoing the CS in favor of simply drawing the automation.  If I have a full track to automate I do still use the CS but its almost getting redundant. I'm not sure I like this development. 

What is CS?  I am completely lost here just trying to do what would seem to be a simple thing.

Control Surface. In my case an original Mackie Control. 

I can use the VS-700 by putting it in Flip mode and using the faders to control Pan, but that is not as exact.

Konrad, don't use the draw tool.
 
Hit F5 to use the smart tool.
 

I used the track drop-downs and selected Automation | Pan.

 
Now, just click on the line. It will add a node where you click. click and drag and it will move the node on the line.
 
Ctrl+click the line between any two nodes and you can drag the line up and down.
 
ctrl+click a segment selects the nodes at either end of the segment. you can then hover over either of the two nodes and move them as a collection right or left or up or down.
 
Holding shift while you do it ensures they ONLY move right or left or ONLY up and down.
 http://www.cakewalk.com/Documentation/default.aspx?Doc=SONAR%20X3&Lang=EN&Req=Automation.01.html