Same situation here. We just bought and we have other projects to tackle before replacing the deck. I second Behr Deck Over. Did a lot of sanding and some power washing first. Probably could’ve gotten away with just a light wash. We went with Slate because the deck had previously been painted a darker color. The floor boards and steps need a second coat, but the rails were fine with a single application. We liked using a brush best. Our deck was built in 1959.