I just starting playing around with orchestra recording using East West Sound products.  Any suggestions on using multitimbral vs multiple instances of PLAY?  
 
Using 30+ instances of PLAY probably isn't the most efficient use of computer resources.  Should I use an instance for each instrument and then add the various articulations to each instrument?
 
 

If I were you I would join their forum and ask there. A lot depends on your setup. If you have a monster computer, you can pretty much do whatever you want. Me, I use several different libraries, EW, GPO, Vienna plus Dim Pro and Cinematic Strings. I use one or two synths of each, and have just a handful of inst's on them. I have heard that maxing out a synth with all 16 channels is not a good idea, the sound quality may suffer. But one inst per synth does drain resources. So perhaps split the difference, have something like 4-6 inst's on each instance. That way also you can group like with like (woodwinds on one, brass on another etc). This helps with applying FX like reverb also (less on strings, more on woods, more yet on brass etc). You will get lots of specialized help on their forum.

I also use the sounds from EastWest ...
I open only one instance of the program and open all the instruments that I will use by dividing them into the 16 available MIDI channels ...
For example: Channel 1: Piano, Channel 2: Violin, Channel 3: Trumpets, etc ...
It's just an example of how I use the software without requiring too much of the system.

I use EWQLSO
 
This is achieved with 5 instances of Play
 

1. Strings
2. Brass
3. Woodwinds
4. Percussion 1
5. Percussion 2

Each Channel in Play is sufficient to drive all of the various articulations for a given instrument
 
Artics are controlled in Sonar by using a drum map for each instrument
I wrote a comprehensive guide once upon a time on how to set it all up
I'll try and find it

Scroll down to post #8
 
http://forum.cakewalk.com/Need-help-with-EWQLSO-Play-m2541513.aspx
 
 

Thank for all the suggestions.   This will be a big help!

Bristol - thank you VERY MUCH for that post - that was extremely helpful.

Yeah it's a bit of a slog setting up all  the drum maps etc, but once you've done it, save it as a template and you'll never need to do it again