4K TVs don't excite me much, you really have to be sitting close to notice much difference, but Dolby's High Dynamic Range Imaging technology, which they call Dolby Vision and which they demoed at CES 2014, sounds amazing. To understand why, I turn it over to the folks at Dolby:

At Dolby, we wanted to find out what the right amount of light was for a display like a television. So we built a super-expensive, super-powerful, liquid-cooled TV that could display incredibly bright images. We brought people in to see our super TV and asked them how bright they liked it.
Here’s what we found: 90 percent of the viewers in our study preferred a TV that went as bright as 20,000 nits. (A nit is a measure of brightness. For reference, a 100-watt incandescent lightbulb puts out about 18,000 nits.)
You may be thinking, “Wow, I don’t want to look at a TV that bright. Looking at a 100-watt bulb would hurt my eyes!” And you’d be right if the TV was displaying a full-screen, pure-white image. That would be uncomfortable.
But real TV images, like scenes in the real world, include a mixture of dark and light. Only small parts of real-world scenes are very bright, and we have no problem looking at them. In fact, one of the secrets to producing TV images that look like real life is having that mix of true brights and darks.
If viewers want images of as much 20,000 nits, guess what the industry standard is for the brightness of current TV images. (Go ahead, we’ll wait.)
If your guess is more than 100 nits, you’re wrong. It’s true—most viewers want TV images that are 200 times brighter than today’s industry standard.
Does that difference really matter? You bet it does. Today’s TVs simply can’t match the depth and detail of a display that can produce far brighter images. And conventional TVs can’t recreate all the colors found in the world around us. It’s a classic case of “you don’t know what you’re missing until you see it.” When you experience a display with much higher brightness, you never want to go back to a conventional display.