My Home: Window Shelf in the Dining Room

I have a dream.  The dream is really pretty broad -having a 'wonderful' and homey home isn't really detailed enough for me as I get closer to believing in my dream.  I want specifics.  As my high school drawing teacher would say, you need to flesh out the details.  I want a house that is interesting, stimulating in some places, calming in others.  I want a house that is clever and innovative where there is practicality -and practicality is a must.  So here is one little detail on the path to creating a great home within a tiny space.

My dining window shelf idea, which I saw in Kurt's Uncle Randy's house the last time we were there for an Easter egg hunt (which is to say that this has been on my project wishlist for a long time. Here we go with another instance where I can say, 'gee, I wish I new a guy who has some carpentry experience who could help us out... hmm...')

This shelf would go across the double windows in our dining room, where we get incredible light streaming through almost the entire day.  (Its one of the things I loved about the house from the start.) The window shelf is great for our house in a lot of ways: artful interest, an awesome, sunny place for plants to freshen the air, fun for Kara, rewarding and calming for me.
Here are some of the fruits of my research...

I had been thinking a simple valance to top the window, since, in my imagination, the shelf is about 3/4s of the way up the window.  But, I really like the top right pic, with another shelf topping the frames (more storage!).  The addition of a decorative glass panel in the bottom pic is really lovely isn't it?(What an adorable kitchen!) But I don't think it will work for my pair of dining room windows as I need the shelf to sit pretty high.
 This one isn't a window shelf (yet it is another great idea!) but I love the brackets.

I will need to learn how to put up shelving brackets, find a stud so the shelf is strong,  and do all this without destroying the walls or the windows. Also, I'll need a board or figure out how to make one.  I'll need brackets: I'm imagining finding something pretty that I will admire every time I look at it.  And finally, time and money.