I was staying in a B&B in Bury and I go up really early and walked up the river for about a mile on the Bury side. There were lovely views at many places of the Arun (the Wildbrooks on the Amberley side are gorgeous too) but what added to the picture was the early morning mist. I stayed in Bury for three days but only had the mist on day one. Good luck - it is a lovely area!