Adding a bit of 'impact' to B&W conversions (getting rid of the grey!)

Hello, I would be very grateful for some advice...

I find I am constantly frustrated by how I am converting my images to black and white. I have read a number of books, many internet articles, and I understand fairly well the techniques/mechanics of the conversion process in RAW or photoshop. But I often find that my images just look a bit... grey!

Unfortunately I do not have the opportunity for hands on experience with a skilled tutor on this, but I am hoping that some suggestions may be available on this forum.

I have uploaded an example from my flickr stream of a photo I took on a recent trip to Paris. This was a long exposure taken shortly before sunset. The conditions were pretty good for this kind of photography at the time, but as you can see my resulting image looks dull and a little lifeless, but I like it as a composition and would like to be able to print this out and have it framed.

Although I use the above example specifically, I am looking for some more general advice on B&W conversion/post-processing as many of my images have similar tones and are lacking in energy that i see in many other similar B&W images by other photographers (and I saw many excellent long exposure images of various Parisienne landmarks along the river for sale in galleries so I know it can be done!). I use CS5 for my image processing, and I also have SilverEfex Pro at my disposal. The image was taken with a 5d mk2 and 17-40mm L lens.

If anyone has any advice or can point me in the direction of useful tutorials/techniques I wouldbe very grateful. I know there are many ways to convert to monochrome, even in just photoshop, and I am keen to try out different methods perhaps I am just not getting the workflow right here?

Many thanks

T.