I normally just trim their whiskers to look even and uniform but last time I was trimming my boy's he moved and I had cut them so unevenly! Too short to salvage so off they went.
I also trim bridle paths, fetlocks and ears. I like the look but I know it isn't for everyone. My mom wouldn't touch a pair of clippers or hair cutting scissors with a 10 foot pole so our horses look VERY different even though they share the same field. Her horses have long manes and tails, no bridle paths and have all of their whiskers while mine have short manes, tails that are just above their fetlocks, bridle paths, and shorter whiskers.