I've been faffing around today in between attending tea parties in the garden hosted by my 2 year old!
My faffing involved hanging a few pictures, re-hanging a few and ditching a few. I'm afraid, along with symmetry, it's a bit of an obsession with me. Now, I am by no means an expert at hanging pictures and arguably there is no right or wrong way to hang things on the wall..only the position or way that pleases you, the hanger!
On the subject of hung/hanged....this is another of my rather irritating pet hates (along with the frequent misuse/over use of apostrophes whenever a word ends with an 's' ! Menus and cafe signs being the biggest culprits!) A picture is hung....a person is hanged.
Anyway. I digress.
A general rule of thumb is that pictures, or any wall hangings of any kind, should be hung at eye level. The centre of the picture being around 5'7"....the average human eye height, apparently.
If you are hanging pictures above furniture, then you should leave around 5-7" between the bottom of the frame and the top edge of the furniture.
These are merely guidelines. I live in an old house with beams and sloping ceilings and relatively few straight walls. I don't ever measure when I hang pictures, much to my husbands annoyance. Everything is done by eye. Needless to say, a few pictures in our house hide a multitude of failed attempts! I do think though, that sticking to the eye level rule is a good start and does work in most cases.
I also think pictures look great, as do mirrors, leaning against walls on the floor.