I've had some people express interest in how I do my B/W conversions, so rather than reply to individual PM's I thought it might be useful to post a thread that might be of interest to others as well. I can't really give you a formula to follow because I don't have one. It's a pretty manual process for me, but maybe this will give you an idea of the approach I take for monochrome images.
I usually do the initial conversion with the B&W Adjustment layer in PS (sometimes I still use channel mixer or Convert to B&W Pro, but the new B&W adjustment layer is my 'default'). I don't try to get too much contrast at this point, because it can introduce noise if you push the color sliders too far. My goal is just to get a full tonal range with at least some contrast between elements that I want to separate. The only other step I do in Photoshop at this point is post-capture sharpening (since I have it turned off in the raw converter).
After that I save to TIF and work on the image in
LightZone. This application takes a little getting used to, but it's very powerful for doing tonal manipulations, especially on monochrome images. The 'ZoneMapper' tool is useful for increasing or decreasing contrast in specific tonal ranges. The 'Relight' tool is useful for increasing contrast, especially if you use it in 'Soft Light' or 'Overlay' mode. Just be careful with that Detail slider as it's a pretty blunt tool. These tools are similar to adjustment layers in that they're non-destructive, so you can easily go back and change the settings, experiment, etc.
I'll usually do some targeted adjustments using ZoneMappers with selections, to bring out texture and detail in certain tonal ranges. I'll also use one or two Relights (one in softlight or overlay, the second in normal mode if needed) to increase the global contrast. The nice thing about this is that if you just used a duplicate layer set to 'overlay' in PS it will crush the shadows on most images (and maybe blow the highlights); but with Relight you can bring the shadows back up some, or tone down the highlights.
For some images it might only take a few adjustments, for others I might have have a dozen individual adjustments targeting specific image areas.
After that, I take the LightZone-edited image back into Photoshop for final tweaking. This might include a duplicate layer set to multiply mode and masked with a gradient to darken the sky a bit more. I might also add some vignetting, either with the Lens Correction filter or a feathered selection and levels adjustment layer. I'll also add one final dose of local contrast if needed, by using Unsharp Mask with a small amount and large radius. Something like amount=10, radius=30 works for some images, others might benefit from taking the radius as high as 120.
After that I add a bit of toning and I'm done.
If you don't have LightZone there are things you can do in PS to work on the tonality of an image. Duplicate layers set to Soft Light, Overlay, and Multiply can be very useful. You'll probably want to use masks and/or opacity slider to limit the effect though. Of course the good ol' Curves tool can work well for some adjustments (again, best to use as adjustment layer with masking if needed). And for dodging/burning, you can create a new layer filled with neutral gray and set to hardlight or softlight; brushing with white brush at low opacity will dodge, brushing with black brush will burn.
Since my workflow is a pretty manual process, and varies signficantly from image to image it wouldn't be practical to try to show a step-by-step example of editing. There are just too many individual adjustments made on each image. What I can do is show you a before/after example.
Here's the color version. It was pretty hazy in the distance, and I knew this wouldn't really work as a color image; but I shot any way hoping it would have potential as a monochrome image.
Here's the intial B/W conversion. It looks pretty awful, I was trying to give myself the raw material to do further adjustments, rather than getting a final result immediately. The important thing was to keep the shadows fairly open and make sure detail was preserved in the tree.
And here's the final version after editing in LightZone and Photoshop. I used selective edits to really push the contrast on the the more distant, hazy portions of the scene without totally destroying the shadows. I also increased the tonal separation of near rock, and added some vignetting. I still wish I'd had a better sky, but this is better than I could have done in color (making such large tonal adjustments to a color image would likely screw up the color).
Hope this is helpful for some folks. I realize it's not an easy-to-follow set of steps, but I don't think there really is a set of steps you can follow since the adjustments are going to be image-specific. If you have any specific questions about something I've mentioned feel free to ask.