Cover Up the Feet
Wrought iron patio furniture is great for weathering the elements, but tough on deck wood. Heavy chairs tend to get dragged rather than lifted when people are getting in and out of their seats. So, you can either follow your guests around and help them out of their chairs or you can cover the chair feet with glides that will allow chairs -- and therefore guests -- to move freely without scraping the wood. You could also use plastic mats that are meant for office chairs, but the glides are a little more slightly.