So this is what I want, (and frankly, had for years prior to X3) and don't know how to make happen. Actual questions in boldface:
 
I want a set of keystrokes to bring up different views in full-screen mode. For all the effort Cakewalk spent making it possible to tile multiple views, it's never been at all practical for me. My eyeballs can only look at one view at a time, and when I'm looking at it, I want as much screen space devoted to it as possible. Much better for me to make it easy to swap amongst full-screen views than dink around with tiled windows.
 
Enter Screensets. I went through and set up my full-screen views and assigned them to screensets. (Never mind that I have to choose the screenset number FIRST and THEN save it, otherwise I'm unwittingly changing the existing screenset I already saved.) But after going to all that effort, I was dismayed to see they are project-based. UGH!!! I tried importing from another project, but that didn't work right. I will never ever want different screensets for different projects. So, I suppose need to set them up in each of my different customized templates. PITA. Is there a way to say "I want this set of screensets to be 'it' from now on, no matter what project I'm in"?
 
I tried assigning keystrokes to specific views, but that doesn't work because although the views do appear when I hit the keys, it tiles with Track View, making neither window now big enough to be useful. 
 
Secondly, I was briefly excited (foolish me) when I saw that I could have different views in tabs across the top of the screen. Well ok, I thought, screw screensets, I'll just line up all the views I want across the tabs and switch around that way. But for some reason, Track View is a special view that can't be added to a tab at the top, or sometimes Sonar wants to tile it with whatever view I have tabbed, or something. Why did they design it like this? I don't ever ever want tiled views. Can't I just have a row of tabs across the top, one of them being Track View?
 
Time and time again I hear Sonar telling me "I know what you want, here let me set it up for you - there, aren't I helpful?" to which I reply, "No, Sonar you DON'T know what I want, so stop trying to help. Let me do it my way." Let me set up my screensets permanently. Let me tab all views across the top and have them stay that way.
 
This philosophy around workflow design, which I see reflected in Take Lanes as well, is driving me crazy. I tell ya, despite the overwhelming amount of helpful assistance from the kind people on this forum, which frankly blows me away, I'm again /thisclose\ to dumping Sonar after 25 years and starting over with DP or whatever. 

jkoseattle
So this is what I want, (and frankly, had for years prior to X3) and don't know how to make happen. Actual questions in boldface:
 
I want a set of keystrokes to bring up different views in full-screen mode. For all the effort Cakewalk spent making it possible to tile multiple views, it's never been at all practical for me. My eyeballs can only look at one view at a time, and when I'm looking at it, I want as much screen space devoted to it as possible. Much better for me to make it easy to swap amongst full-screen views than dink around with tiled windows.
 
Enter Screensets. I went through and set up my full-screen views and assigned them to screensets. (Never mind that I have to choose the screenset number FIRST and THEN save it, otherwise I'm unwittingly changing the existing screenset I already saved.)

 
If you want to use a screenset as a base for another copy it to a slot and adjust as required.
 
 

But after going to all that effort, I was dismayed to see they are project-based. UGH!!! I tried importing from another project, but that didn't work right. I will never ever want different screensets for different projects. So, I suppose need to set them up in each of my different customized templates. PITA. Is there a way to say "I want this set of screensets to be 'it' from now on, no matter what project I'm in"?
 

 
Set them up as required along with all your other project based preferences and then "save as " your "Normal" template. That will then become default for normal projects.
 
If you are having trouble importing screensets make sure there are no locked screensets in the project. Locking them is a way of selectively importing.
 
EDIT: Just to be clear, locking them in the target project (not the source) stops them from being imported
 

 
I tried assigning keystrokes to specific views, but that doesn't work because although the views do appear when I hit the keys, it tiles with Track View, making neither window now big enough to be useful. 
 

 
Again I would check you don't have locked screensets. If they are locked they "forget" changes made in a session and revert to how they were before said changes.
 

Secondly, I was briefly excited (foolish me) when I saw that I could have different views in tabs across the top of the screen. Well ok, I thought, screw screensets, I'll just line up all the views I want across the tabs and switch around that way. But for some reason, Track View is a special view that can't be added to a tab at the top, or sometimes Sonar wants to tile it with whatever view I have tabbed, or something. Why did they design it like this? I don't ever ever want tiled views. Can't I just have a row of tabs across the top, one of them being Track View?
 

 
NO but you can tab loads of other views in the multidock and then use the "D" key to hide and show them. The track view is the only view that can't be tabbed.
 

Time and time again I hear Sonar telling me "I know what you want, here let me set it up for you - there, aren't I helpful?" to which I reply, "No, Sonar you DON'T know what I want, so stop trying to help. Let me do it my way." Let me set up my screensets permanently. Let me tab all views across the top and have them stay that way.
 
This philosophy around workflow design, which I see reflected in Take Lanes as well, is driving me crazy. I tell ya, despite the overwhelming amount of helpful assistance from the kind people on this forum, which frankly blows me away, I'm again /thisclose\ to dumping Sonar after 25 years and starting over with DP or whatever. 

Again I would check for locked screensets. I have a load set up that I find very useful and if you want an insight in to what can be done with them check out this thread.
 
HTH

Aha, with D I can show/hide the other views. Conceptually, it's very confusing that Track View can't be tabbed but everything else can. Now that I know about what D can do, I don't really need to mess with screensets, though your Locked thing sounds exactly like the cause for the trouble I was having. 
 
I have all my views set up with tabs, looking good. I know at one point the tabs were at the top, but now they're on the bottom. How can I get them to the top?

Choose to dock the multidock at the top instead of bottom. It's in the multidock window menu which you'll find toward the bottom right of the multidock.

You can also drag and drop the Multidock just about anywhere. 

jkoseattle
Now that I know about what D can do, I don't really need to mess with screensets,
 

You'll be surprised what you can do with screensets and the multidock with a little out the box thinking.
 
Want to see 10+ sends per in focus track in the Console View? Or how about a time line in the console view? Switch between a dedicated track console and buss console with one keypress? Switch between track views at different zoom levels with different edit filters set, etc. etc.
 
Screensets can do all of that and much more. They are without a doubt my favourite feature of the X series - like the old layouts on steroids. I wonder how I got by without them.
 
Have I mentioned I think screensets are great?

FastBikerBoy
They are without a doubt my favourite feature of the X series...I wonder how I got by without them.

 
Same here. Screensets were my primary reason for upgrading. Before that I was happy enough with Sonar 7. The only thing that used to frustrate me was the need to keep opening and closing different windows or selecting different tracks in PRV. Screensets solved this problem.

I'm loving screensets more & more, now that switching between them no longer crashes Sonar, which was the case for me in X1 and X2

FastBikerBoy
 
Screensets can do all of that and much more. They are without a doubt my favourite feature of the X series - like the old layouts on steroids. I wonder how I got by without them.
 
Have I mentioned I think screensets are great?

I often find myself wishing Windows had screen sets.  It would save me having to set my environment up everytime I turn my computer on.
 

Is there a default keyboard shortcut to move from tab to tab in the multidock? I can't find one.