I found that if I set the Radius up even higher (20) I could use the Opacity as a single adjustment slider. In some images I dial down the Radius, and in some I just use the "Clarity" Preset selectively using Control Points.
I also found a useful preset combo that mimics the Vibrancy slider too while I was searching.
Select Color Booster from the Color Menu Set the Level to 25% Apply Luminance & Chrominance Opacity Set Blending Mode to Darken Set Liminance Channel Opacity to 0 Set Chrominance Opacity Channel to 50%
If you have a look at my Gallery I just posted an image I took earlier this year. An otherwise flat image has mainly been transformed by using the Vibrance and Clarity presets discussed here... plus a little extra sharpening and contrast curve.
I use a multi step process in CNX2. First I set a Picture control with zero sharpening. After I do early adjustments like Noise reduction, lens correction, highlights and shadows and B&W points I then do a USM capture sharpening for my D700 using 40, 7 and 4. I then work on my image with selective tools. hen I am done I run the CEP30 filter Tonal Contrast which is really a 3 step Hi Pass filter for highlights, midrange and shadows. Finally If I think it needs it, I run a HIRADLOAM USM on the file and then adjust the result using the attached opacity filter often setting the blending mode to darken. I find I can run Intensity between 2-12, Radius anywhere from 80-100 and threshold around 28.
If you bought any of the NIK filters in the past you can download the whole suite for free and use it stand alone. If not you could do the same things with a bit of work using CNX2 alone. For example the Tonal contrast filter is just a hi pass filter that applies separate settings for the highlights, midtones and shadows. You can replicate it by using the Hi Pass filter 3 times selectively but it is much more work.
I tried out Nik Color Efex after one of the comments made above. I completely endorse what you are saying about the ease of making these sort of changes with CEP!
As it happens I have a trial version of CEP3 and I'd love to activate it. The integration with Capture NX2 is really strong and I'd much prefer to use CEP3 rather than 4. Now all I have to do is figure out how to get an activation key for a product that is no longer sold by Google... if anyone has any ideas on that I'd love to hear from them!