Thanks for the comments Guys!
Munchy: I tried to give some idea of scale on the tower of Yarthraak, with the horse and rider crossing the bridge, but I guess it wasn't too successful. And, yes, the claw on the Dragonlords' citadel should have been a bit more claw-like!
One of the other problems I get, as well, is the texturing.
Generally, the modelling is done using Imagine, which I've been using for years- and has some superb procedural textures. And, in Imagine the scaling of textures is very precise- you can actually see the size of the textures' 'axis' and scale and move it within the object, which enables you to quickly set the basic size and shape of the texture(s) up. (Additionally, you can layer almost any number of image maps and procedural textures one over the other in Imagine.)
Then, it's just a case of tweaking the various texture parameters, to get the final effect you are after.
But, when I do more landscape type images, I convert the objects to Bryce 5/5.5. Bryce's procedural textures on the other hand, are a lot more hit and miss getting them scaled. Waves on water is a good example- they can be difficult to get looking the right size. Requiring repeated test renderings- and Bryce is quite slow at rendering: the price of using Volumetric Objects. Additionally, layering differing textures can be difficult in Bryce.
On the other hand, Bryce does have some nice textures- if you don't mind playing with maths formulae...
All the Best,
Kevin.