I hate the generic genres, I use ones i make like "ambient alternative" , "Indie Pop", "Folk-Rock", et al. to be more specific.
I too make playlists of certain "sounds" however like "Modern Acousticish" for softer rock, acoustic, some softer indie, folk, and other softer influences. Then there's "Chill Out" which has some of those same sounds as that but more focus on ambient music and includes some electronica stuff. Then there's a pretty obvious "Indie/Avantgarde" playlist I have... Much better for getting only certain songs you want in lists for when you want randomized selections of certain sounds (and when smart playlists do not suffice).