Thanks for the comments. I must confess: No2 is straight from the camera taken with a custom monochrome setting and Y2 filter effect. The others are converted from RAW to B&W in Lightroom 5 using a custom preset from Matt Kloskowski at
http://lightroomkillertips.com/category/presets/" onclick="window.open(this.href);return false;
I have been experimenting with mono lately - I just feel that it takes me back to my roots somehow and I become more of a photographer and less of a snapshooter. If I set the jpg sharpening to zero, the D7100 without AA filter seems to lend itself to smooth gradations in mono, but I have more options converting in LR5 from RAW, using either the same presets as are in-camera, or custom presets which I have downloaded. Either way, replicating good B&W as I once was able to produce with a 6x6 and a fully equipped darkroom, using a digital process, seems to have quite a steep learning curve, and I haven't even got to the printing stage yet.
Life is so short......