Some say, that the sound of a string quartet is so homogeneous, that the composition must be first class. Otherwise it will be difficult to bear listening. I can definitely relate to that. And I am sure that there is a lot more music for string quartet available than what I have heard. But then again, in my humble opinion Kronos Quartet is a very good place to start.
It must have been 1989, when I read about Kronos Quartet playing Thelonius Monk. I was intrigued. So I went to a nice record/CDs store and asked for it. They didn't have it there, but they did have this album featuring music by Terry Riley. I took it, without knowing anything. It turned out to be a very pleasant surprise for me.
The compositions on the album are lengthy pieces. To me it seems each is trying to tell a story, or rather to guide ones imagination to a series of scenes, like in "The Sunrise of the Planetary Dream Collector". The compositions are more on the calm or quiet side. They are pleasant without being easy.
In the same vein and written also by Terry Riley is "Salome Dances for Peace". 2 CDs, close to 2 hours alltogether. I can listen to all of it in one go, if I'm in a fitting mood.
Kronos Quartet has been performing since 1973. They seem to be one of the most successful string quartet. A huge number of compositions have been written explicitly for them from all over the planet. They have performed so many genres and made so many experiments --- one might be tempted to use a number of superlatives. String quartet is not everyones favourite, however, I you are in an adventureous mood, give it a try.
A good example of featuring other genres is an adaption of Jimmy Hendrix' "Purple Haze" for string quartet. Kronos Quartet has been performing with Astor Piazolla (5 Tango Sensations), Modern Jazz Quartet, Björk, ... you name it ... all the way to Hazmat Modine (Dead Crow).
Cheers,
~ew
wikipedia: Cadenza on a Night Plain (1984)
wikipedia: Salome Dances for Peace (1989)
youtube: Kronos Quartet --- Purple Haze