Go into a shop that sells framed prints.  Pick out 10 items that you
wouldn't mind having in your living room, bedroom, dining room,
sunroom, bathroom or behind the toilet door.  Try to identify what is
common to all 10 pictures.

We don't know your taste, you do.

Poster shops make a living by guessing what people might like.  Why
not go to one and see what kind of pictures would seem to make your
life better.

Anything that the owner of the wall deems suitable for his tastes and decor.

You should hang pictures you like to see frequently, and
would like visitors to see.  The first kind can hang in less
public places, like a bedroom. Those meant for you and for
visitors can go in a more public place, like an entrance
hall or living room.  What you put on a wall in an office is
another matter; you are showing your tastes and interest to
a certain audience.  In any case, it is for you to decide
(with important input from your boss at work).

Submit your short list to PhotoSIG.com and hang the ones that score 30
points or more.

My choice is something special but muted in terms of message.  Here is one
that has enhanced several walls in my residences:
http://home.comcast.net/~charlesschuler/wsb/media/291308/site1052.jpg

Subject matter doesn't matter as long as it's not offensive to any group or
subgroup who is likely to visit your abode/office, or hear about the
contents from someone who HAS visited your abode/office.

In particular, you want to avoid any political statements or expressions of
religious or sexual preference (like that fall shot off the Blue Ridge
Parkway, where that little church way down in the Valley snuck in) else you
open yourself up to a lawsuit.

I would also stay away from pictures of beautiful people, as that may make
folks wonder what you are really up to. Likewise shots of children and of
course, all shots of family members MUST be approved in advance (in writing,
if you can swing it) and NEVER posted in a public place where they can be
seen by someone who might wish to do you harm.

I'd also avoid any shots that include animals (lots of people are afraid of
dogs and allergic to cats and barnyard critters can have "certain"
implications some parts of the USA, if not the world at large.

For an office or home environment, "bland" is the order of the day, stick to
tight shots of flowers and you should. be ok, as long as they are not red or
yellow (the color of blood and paranoia).

For the home environment, make sure the colors match your couch and the
frame matches the decor. At work, the "taste police" will keep you in line.

Just make sure that the pictures will not get you or your family in trouble
if you are ever visited by the authorities, friends, relatives, or a
disgruntled spouse.

DP

Simple.  I print and frame the ones my wife tells me to print and frame.
Normally they are printed in the 16x20 size range.  At the moment, in the
den, I have two film prints from scanned negatives, two prints from a
digital Rebel, one (16x20) from a Canon Elpf (5mp), and a 11x14 from a Nikon
3mp.  The large print from the 3 mp camera is soft in detail when viewed up
close, but quite pleasing when viewed at a normal range. All are different
categories of scenics.

Ones you really, really like.