Thanks again everyone.
Mahnmut, I spent yesterday playing around with the texturing and the colouring of the rocks, but because of the way I'd initially set it up, I can't get the grey to show up in a realistic way. Presumably it's because the red sand has displacement applied to it, but for whatever reason, the grey only shows up on a few of the rocks and then it looks too stark and out of place. So I've given up on that front - I'm weak, and I lack resolve
(plus I have an exam tomorrow that I should really have been revising for!)
Oshyan, I totally agree. My initial aim was to just go for a very natural, intentionally boring image. For me, the images of Mars that are "boring" are, ironically, the most exciting. I think there's something really evocative about seeing something that is both seemingly normal and mundane while knoeing that it's truly alien.
Anyway, I've since been trying to explore dhavalmistry's recommendation of adding a rover, just to apply some focus. Unfortunately I can't find ANY free rover models, and I don't have the cash to spend out on one. If anyone has any suggestions on this front I'd be most appreciative.
Thanks,
Inscrutable