You know what I would do twotogo, is to print off a couple of pictures of your mantle and work with some colored pens and try painting your mantle dark try removing everything off the mantle and maybe just two hanging pictures on either side.. with the same dark frame as your mantle.. just a thought...
Huggy

myself I love your mantle the way it is..just my opinion..as for the decor, it depends on the style, my guess is that you are going somewhat rustic with a tad contemporary..am i right?
I think i would find 2 long narrow matching pictures or mirrors or pieces of art and center one on each side wall of the fireplace above the mantle, one thing that really looks great is to layer..so if you use mirors or if you use an outdoor scene ..say with a lot of grasses..you could layer your grasses in front of and below the art on the wall..to tie in the art to the mantle, and then add a few other outdoorsy things to the mantle..the photographs are too small for there, put them somewhere else..although lovely they are just not the right scale..

do you happen to have a rock collection? it would be pretty on the mantle with an outdoor picture of a stream going over rocks along a meadow? with the grasses..

or a few beautiful unusual rocks on the mantle with the grasses..or a hurricane lamp with washed river stones filling it..clear glass..to tie in the rocks of the fireplace with your art.

tell a story about what you like, if you love horses a horse running through a meadow, if you love old mills, an old mill with a creek and some old wooden architechtural pieces..

a tall grouping might work in the center going down to a shorter one on each side..or a tall one on each side of each wall with shorter in the center..

maybe two long art or mirror pieces, a much taller grass in the corner center and the smaller grasses just over the edges of the art on each side..

there are number of ways to do this..but you love it..leave it white unless you hate the white..i don't..i think white and stones is very updated rustic

Wow, I really LOVE that stonework. Is it real? It's so dreamy.

I think what you need to do is unify your beautiful artwork. It doesn't have any cohesion. The best way to do with, IMHO, is with frame color. I like the color of the frame on the left... imagine if all your frames were the same color...?

wow! Thanks all....your ideas are awesome :) I am so thankful for this forum....really I am considering all your ideas except painting the mantle. I do love the white and we have white base and crown throughout the house.

mclarke, the stone is Cultured Stone, not real, made by Owens-Corning.

I would move the picture compositions closer together. Prop the tallest in the corner where the two sides meet and put the smaller two pictures on either side of the large one. Then move the grass closer in on each side and see how that looks.

I did this with MS Paint so it's not beautiful :-)
I used what you have and didn't add anything, just an idea.
Btw, Bebe is adorable!
Your stone is beautiful too.

With the strong black-and-white elements (including the lovely cat LOL!) -- how about simply taking some of your photos -- change them to black-and-white; mat in white and frame alike in black to create a simple but effective family (and cat!) gallery wall.

Then simply add the two grass displays on each end BUT paint the boxes to black to show up against the wall.

For a party during the summer - add a simply chunky white vase or pitcher with herbs and flowers on top of the stove ...

Jan