wild but mild starter

I have adapted the sourdough starter recipe from SourdoLady sucessfully to make whole wheat sourdough.  After reading a number of books, I have been trying stiffer starters in the interest of creating a more mild and more complex taste.  While I have been able to get the sourness toned down from vinegar to yogurt-like, I have only once achieved a complex flavor (tasted like a mix of cheese pears and nuts).  If anyone has had luck producing complex but mild sourdoughs, I would welcome suggestions for formulas and refresh timings.

 Thanks