Overcomplicated NPCs are my bread and butter. I think that multiple classes/prestige classes and templates only enhance the backround of a character and make them more interesting. For example, a reocurring villain in my Eberron campaign is a Female half-elf Necromancer5/Ranger3/Eldeen Ranger of the Children of Winter1/EldritchKnight3/Havoc Mage3 (that's a bit much even for me)but all of her prestige classes are directly tied to her storyline (she trained amongst the rangers of Valenar though she was already a necromancer, it is a natural progression to be an eldritch knight, and the havoc mage was just thrown in because I was getting bored of the vanilla abilities of the knight. She now leads a large cult of the Chiildren of Winter druids and rangers...Most likely they wouldn't except her if she wasn't a Child herself. So there you have it, sometimes you need to have alot of classes to achieve the character you are looking for.