Resist the urge to cram stuff in every empty spot in the house. Leave well enough alone.

Remove some of the smaller pictures and put one or more taller items such as a vase or sculpture. Too many small items becomes cluttered looking.
Your treasures will have more impact if they aren't crowded together.

I would find two framed art pieces and hang them there (your #3 question). Something coordinating, if you like symmetry. If you prefer asymmetry, then one framed piece on one side and a larger sculptural element on the other side (like a large vase or 3 dimensional piece). I'd leave above the tv empty and be very careful about what to put on the top shelf. Not a bunch of little things, but something cohesive like a collection of larger pottery or wood items or something more horizontal than vertical, but still with enough heft that it doesn't look tiny up there.

[Beach Style Home Office[(https://www.houzz.com/photos/beach-style-home-office-ideas-phbr1-bp~t_732~s_2110) by Dallas Interior Designers & Decorators CDA Interior Design

Here is one where they added a lamp to a larger opening..that might work for you, if you like that idea.

[Traditional Family Room[(https://www.houzz.com/photos/traditional-family-room-ideas-phbr1-bp~t_720~s_2107) by Christiansburg Interior Designers & Decorators Interiors Unleashed

This post was edited by olychick on Sat, Nov 29, 14 at 3:01

Just install a matched set of prints with nice frames up on the wall and call it a day. Also, it appears as though you could use an extra shelf in that wide open space in your cabinets.

I agree with Junco. I'd add large/tall vases with a pop of color on each flanking side. That will fill in the extra white space without overcrowding. As hollysprings stated....I'd definitely resist the urge to fill all spaces. Especially with little things that all need to be moved and dusted. Plus it will just be too busy. The first pick that olychick posted has several great ideas. I take it this built-in is in the family room??

Let's see:

1)Above the cabinets:

Leave those spaces empty for the moment!

BUT -- consider adding large simple matching elements -- like large white-painted wood bowls or ceramic or pottery oval or round platters (on their edge) again -- think of strong, simple lines! IF you need to elevate them -- then add some books or even a brick or two to correct the visual height of the objects ....

2)Space above the TV:

Handle decorating the shelving first -- and leave that space open -- to let the viewer's eye "rest" ....

3)Two Large Middle Spaces:

Take two photos of trees in your yard or your area -- have them enlarged and re-done in black-and-white -- frame in a wide white mat --and then add thin black frames. Hang these photos in those middle spaces .....

4) Create a Gallery Wall:

Then take your family photos -- and create a family gallery wall with long white wall shelves to lean some of the larger photos -- AND then hang the smaller ones ......

Have you considered removing the glass doors and shelf inside each or taking the shelves to the ceiling (without the glass doors). If not, I would leave it all bare. The eyes need places to rest in a room.

I like the photos olychick added: lamp in one. Artwork in another. Or add shelves to those larger areas.