Thanks to you all for your comments. I have just been using the Topaz Clarity tool again on the original image (after sharpening), and it is indeed quite powerful. It has much finer-grained control over structure than Lightroom and Nik Viveza (unless I haven't learned its full capabilities).
In the end I have decided on smoother steps, while increasing structure in the high-contrast areas. Like Izzie, I prefer this effect. I also reduced the highlights in Topaz Clarity, as I had unwittingly blown them during my last PP. (I found the histogram tool in TC today
)
Below is the result. And below that is a screen-shot of the Topaz Clarity settings that I used, to give you an idea of what it can do.
Tony