I found a really good program on BBC Radio 4: National Treasures from August last year. They debated the question: Should we spend £500 million on preserving the natural landscape of the Thames Estuary or transforming Stonehenge into a visitor attraction worthy of World Heritage Status? It was all just a theoretical exercises but gave me some good ideas about how investors, politicians and academics think about places and if they are worthy of preservation. (This idea is of course in stark contrast to proposals like Heathrow's third runway in the estuary). The panel argued around historical, emotional, social, and existence value.
Words like melancholy, decay, love of ruin, wilderness, despair came to mind for emotional value. (I'm always desperatley drawn to places of such character).
Problems with access to the estuary was mentioned which can not be understated, it is of course much due to this that it holds its special character. Germain Greer called the estuary the cradle of Britain's industrialisation, one of her many good points I thought. Finally, not to my suprise, Stonehenge scored the higher points.
Other words to think about: mud, intertidal zones, marshland, biodiversity, rising sea levels, changing light, interlocking system, sewage.