Sound design is usually considered as a two-fold profession. There are designers who specialize in live sound (for musicals, etc.) and there are those who specialize in "creative" sound design. I fall pretty fairly into the latter camp - I've designed plenty of musicals, but I often consider such things a kind of paint-by-numbers approach.
I do have a specific aesthetic in regards to live sound, however. Whenever possible, I like to keep my music and vocals on seperate sound systems - this allows for the full range of musical expression to come through without the extreme EQ often demanded of 20 or so wireless microphones when the mix is all on the same set of speakers. This also keeps costs down - no need for extra-fancy mixers and external matrix processors and all the hoo-haas that come with them. I am also a strong proponent of mixing as one would an album - there are many sound designers who prefer everything to sound "live," which is admirable, but let's face it - most folks are (even perhaps without knowing it) much more sophisticated in their desires as far as sound is concerned. This opens up the world, as I see it - there are all kinds of things one can do with sound processing that aren't necesarilly natural, but have a subconscious effect on the listener.
Regardless, I do prefer to work on the creative side - creating things like period sound beds and sounds that don't necesarilly exist in the real world. Here's a white whale breaching and confronting Ahab before sinking back into the ocean for the production of Moby Dick Rehearsed
And I was called on to create a scene wherein a squirrel chattered to a character before getting frightened and running off.
Sometimes, I'm called on to create multiple strange noises for a production. Such was the case for Dream of a Common Language, whose script calls for all kinds of oddness. Here's a sample.
And finally, for a production called In Delirium, the author/performer wanted a specific song performed by Renee Fleming, but he wanted it to sound like the imaginings of a crazy person. I made several iterations for the show, but this version combined them to some extent (it was also the curtain call), and it makes sense as a piece of music as well as an example of extreme processing to heighten the mood required by the production. "Lascia Ch'io Pianga" by Handel: