I watch quite a lot of TV and I write about it here a bit too. Nowadays, most of my programming is designed for the 16x9 screen. It's not so much that I'm still impressed with high-definition, it's more like watching programs in standard format sucks.
If I were to choose a single program that makes the best use of the improved HD medium, it'd have to be CSI: Miami. The quality of the camera location, video capture, and editing is light-years ahead of many other shows. Nearly every scene this season is eye candy. It is shot a bit on the yellow side of the spectrum but assume that's a technique to emphasize it's taking place in a semi-tropical location. Interestingly, the CSI: NY tends to have bluer hues by comparison.
I would have to say that as far as the use of editing to advance a storyline, the crew of CSI: Miami consistantly beats out many high-value Hollywood productions.