How to place speakers at the optimum height

OK Agoners, How do you determine and place the speakers at the optimum height? If it's book shelves than it's pretty easy, you just buy an adjustable speakers stand and try it out. But what if you have floor standers? Are they already design to be at the optimum height? I don't think it would work for everyone since there are 6'5 guys and 5'6 guys so ears level are different. Is there any "audiophiles" lives in the vicinity of 95138? I like to check out some other people system to compare to mine and see what I'm missing if any. I'm pretty new to this high cost hobby so I would appreciate it if someone could show me their system. Thanks.