Exporting (or some other "operation") a mix from a portion of a project

For some reason I can't seem to find a combination of search words/phrases to pull up any useful threads addressing my question, so I guess I'll have to start a new one.
 
What I have is a project consisting of 12 tracks recorded of our rehearsal which lasted roughly 3 hours.  We were running through about 8 songs, trying two or three takes each, and maybe focusing on cleaning up some parts of the songs.  I just left the recorder running during the whole session, so it is all recorded as a single session of 12 3-hour tracks.
 
Generally (but not necessarily always) our last take was the best.  What I want to do is "export" (or whatever) my stereo mixdown (which has compression, reverb, automation and such) of just these best takes.  I don't want to split the session into separate projects for each song, I just want to specify something like "write my mix of this project from 16 minutes to 20 minutes to a stereo wave file called mysong.wav".
 
If I just do an export it creates a wave file that is a mix of all 3 hours of the project.  I've tried to set starting and ending points (like defining a loop start and end), but it doesn't seem to respect those limits in the export.  I have markers that I could specify as start and end points for the mix, but I don't see a procedure that would let me specify them.
 
I'm guessing it must be something simple that I can't find 'cause I don't know what the proper term is for it, either in the user interface, or in the forum search.  I'd assume that this would be a reasonably common scenario for users to deal with.  Perhaps I look right at it and don't invoke it since it doesn't click for me as the thing I need to do.
 
The one thread I saw relating to the issue was about creating 8 (or whatever) new projects, copying all 12 of my tracks to each project and then trimming away the previous and following parts of each of the tracks (such that I just had the portion of the tracks with the take I want to mix) in each of those 8 projects.  I can see how that would work, but wouldn't I end up with 8 copies of my 12 3-hour tracks after that?  Since Sonar does non-destructive editing, wouldn't the entire 12 3-hour long tracks remain in each of the 8 projects even after I trimmed the preceding and following parts of the tracks?
 
Thanks for any guidance or suggestions,
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Greg
 

Wow, thanks Anderton for the quick response.  I will attempt those this evening when I get back to my mixing task.  I figured I'd be lucky to have an answer by the time I got home.
 
Actually, I thought I had done essentially your first suggestion, but my result had been the entire 3 hour session in the output file.  It may be though, that I did the wrong order.  I had the limits of my song selected in the time line as I was working on the song (with markers at each end, and the loop points set too so that if it went to the end it would go back to the start of the song), so I thought that was fine and then when I was ready to save the mixdown I individually selected all the tracks that had audio (a couple weren't active in that song, so it wasn't actually a "select all" operation) and exported.
 
Regarding the third option, isn't there an "autosave" option that automatically saves every few minutes?  Maybe not (or perhaps it is something that can be enabled/disabled), but I could just see myself getting caught by something like that.  Just after trimming my 12 tracks autosave would fire off.
 
But regardless of the autosave (or not), does that imply that Sonar's non-destructiveness only lasts until you save your project, at which point your changes (such as the trimming) become permanent?
 
Thanks,
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Greg
 

You can also 'select all', then click on the Now Time at the point you wish to start the export, click on Edit > Select > From = Now, which will tell Sonar that you want the export to use the Now Time at the point you just set it to.  Then, scroll over to where the ending point of that piece you want to export, again click on the Time Line to set the Now Time to your ending point (all tracks should still be selected), and click on Edit > Select > Through = Now, and this will tell Sonar where you want to stop the export.
 
After selecting the tracks and setting the From and Through times, you should see the selected portion of the Time Line a darker gray, and the selected tracks as well should appear darker.
 
Now, simply export your audio and give it an appropriate name, and celebrate by having your band mates order you pizza for doing all the work.
 
There are usually lots of ways of doing things, and it comes down to which you find brain-friendly.  :)
 
Bob Bone
 
Bob Bone

Thanks to both of you!  I now have a good idea of where I went wrong and what to try tonight when I return to my project :-)
 
I also see that I have some research to do to understand the details of save/auto-save, and the associated options of saving all audio or one file per clip (and whatever else might be available).  If you can suggest a good resource with explanations of such things, I'd appreciate that.  Otherwise I can probably do some experimentation.  I'm thinking that might provide insight into how I might be able to separate my 12 3-hour long tracks into 8 separate projects (one for each song with all the takes in it).  Understanding what trims and what doesn't would be key.  I thought if I tried that I'd end up with 8 copies of my 3-hour long tracks, each displaying just the section that applied to the associated song.
 
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Greg