This is a RAW image conversion test. The image used was taken with a Nikon D200 as a RAW .nef file. The purpose of the test is to show what can be done using ACR (Adobe Camera RAW) exclusively for a black and white (BW) conversion rather than performing the BW conversion within Photoshop itself.

There are four versions of the image presented. One is the ACR conversion and the other three are for comparisons to the ACR BW converted image. All images are re-sampled down to 720 X 482 pixels from their original dimensions and saved as standard 8-bit .jpg pictures. This picture, unfortunately, is overexposed in the high whites so no gray detail can be brought out in the sky. The nature of this image does not lend itself well to showing dramatic differences between the conversion methods.

Versions:
1-ACR BW conversion exclusively using ACR sliders.
2-Next is the color .nef file converted with factory 'default' ACR settings and converted using 'Image->Mode->Greyscale'.
3-Straight factory 'default' ACR settings before converting to BW with 'grayscale'.
4-ACR BW conversion with three step sharpening.

The purpose of the 4th image is to show some of the effects that sharpening has on the contrast and final look of a black and white image. You will want to consider that when doing BW conversions.

Be advised that most BW images will have the full range of tones from pure white (255,255,255) to pure black (0,0,0). Use the eyedropper tool to be sure that the parts that are supposed to be pure white really are and the parts that are supposed to be pure black really are. Don't trust your monitor display even when it is calibrated. If you need to do further global adjustments in Photoshop to set black point and/or white point I recommend using "Selective Color"(White, Black and Neutral) for adjustments rather than standard ways of setting white and black points. You have more control that way.
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The next two are an unadjusted .jpg and an adjusted .jpg. This shows what I'd do to that particular .jpg to reduce flatness and retain midtones. They are:
1-"Levels" adjustment layer to set white point in lfet BG sky.
The assumption is that the BG sky should be solid white. It isn't so white point is used to set it. You can see from the histogram that this adjustment is needed. The unadjusted image has a gray sky.

2-"Selective color" adjustment layer to brighten foreground and add some contrast but retain nice midtones.
Setting changes are are Neutral:-20, Black:+5 and all others unchanged.
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The last image is a BW further adjusted with a slight "S" curve contrast boast with "Curves" and a toned down the neutrals (-15) and increased the blacks(+15) in a "Selective Color" adjustment.
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