The most interesting way of incorporating strings into rock music that I've heard is the music of Electric Light Orchestra, which was almost like incoporating rock and roll instruments into classical music (depends on the song). However, I don't know any websites that have articles about strings in rock music, my suggestion would be to google it and don't stop looking after the first few pages.
Indeed, I prefer to only divide when it would be helpful to the piece, rather than dividing for the sake of looking different.
This is what I was thinking might be the answer to the question about getting a "lush" sound. I'm assuming four part writing will give you the strongest sound and it will sound "lush" if those parts include the "color tones" of the chords in question (I put that in quotes because I'm not sure if that's the term I'm looking for).
I am trying to write for the musical theater. I have the Sebesky book and it is a great starting place for the strings and other sections. But it deals more with the recordings studio, rather than live performance. And a theater pit orchestra is an even more specialized situation. (Years later Sebesky won a Tony award for his orchestrations for a revival of Kiss Me, Kate. It's brilliant.)
The thing to remember is that musical scores are not always written in the jazz/big band style. Once upon a time they were, but these days a show can be in virtually any style. And you can't always count on your rhythm section to carry you through because in some eras it's just wrong for the period.
The big problem is making a small number of insturments sound like a larger orchestra. The strings especially. It seems like most shows just give up and score for a string quartet and mic the hell out of it. Most, double that with a keyboard playing string patches.
The show I am writing is set in th late 19th century, when big orchesrtras with a lot of color and very subtle transitions were the rule. I didn't want it to sound contemporary, so I confined keyboard use to those instruments where I thought it would be least detectable (piano, organ, harpsichord, harp, glockenspiel, celeste sounds). For my string section, I chose 3 violins and 1 cello (+ string bass). I usually have the 3 violins in unison, when other instruments are playing. (Or 3 violins + 1 reed in unison). So I can have 2 part harmony (violins and cello), or the violins playing the melody and the cello doubling the bass (in unison or at the ocatve). If I need more harmony, in the quieter passages I use the 3 violins divisi, adding one or more woodwinds if I need more parts. When underscoring, I arrange the three violins and cello like a string quartet (though sometimes I add the bass -- to make 5 parts, or I score it for 2 violins + cello + bass).
Since my vocals have difficult intervals and can be quite rangey, I often need to have the melody in the chart somewhere. I find that the three violins in unison usually works best for the solos (and a single wind instrument in the chorus numbers). Lately, I've been experimenting with three part violin harmony for this, or in doing a truncated version of the melody, which just includes the difficult notes or intervals . . . but that usually leaves me with a very dull violin part. I really haven't been very adventureous, because I don't know what I am doing and I can't find any good advice on how to accompany vocals in a muiscal. (Yes, I know, it's better to have them isolated, so they stand out, but this doesn't work in practice for a lot of my score. It makes it too hard to sing. I need some support for the singers but I am seldom sure what to do, so I have been very timid with the arrangements in this respect, opting for making sure they can hit the right note above all else.)
I am nearly finished with my "full" orchestration (17 musicians + conductor, or 16 musicians with conductor playing the second keyboard which is intentionally a simple and sparce part). This fits the union minimum for most of the bigger Broadway houses under the current contract. Once completed, I am planning an expanded version for non-professional productions where nobody is getting paid and they can afford to have a bigger orchestra -- which will be much easier. (3 first violins, 3 second violins, 2 violas, 1 cello and 1 string bass).
Finally, more importantly, I will need to do a reduction for small professional theaters. According to the Dramatist's Guild's latest Resource Directory, the smallest house requires an orchestra of no more than seven musicians. This will be the score that any venue gets if it can't afford the full score. I am putting this off until last, because I really don't know what to do with it. I suppose I could go with bass, drums, and 3 or 4 keyboards replicating all the other instruments + one or two solo wind instruments (flute and/or trumpet) but this seems a very disappointing way to realize a score that is supposed to evoke the era of Debussy, Mahler, etc.) I'd like to find a better way, but it seems like I would be sacraficing too much in the way of harmonies. Maybe a better approach would be to go with two pianos, bass and drums.
I have suggested that NS should start a separate forum for musical theater composers/orchestrators. I know there aren't many of us. But this is such a specialized area - especially if your score isn't contemporary sounding - and a lot of the "rules" for other types of orchestration don't apply here (or apply very well). It helps me a lot to see what challenges others are having and how they solve them.