CampingWorld.com, MilesKimball.com and Amazon.com all sell picnic table sets that include bench covers. Walmart sells the bench covers alone or as part of a kit.
CampingWorld.com sells a three-piece picnic table cover set that includes two padded bench covers. The set is made of nylon with elastic straps to keep the bench covers in place. The set comes in either white and red or white and blue checks and fits tables up to 6 feet.
MilesKimball.com sells a similar set. However, all three pieces are made of flannel-backed vinyl. Likewise, the edges are elasticized so they fit snugly over the picnic table bench instead of on top. The bench covers can accommodate benches up to 60 inches long and 16.5 inches wide. The sets come in blue or red.
Amazon.com has a wide array of picnic cover sets that include bench covers. The Coghlan's brand receives high reviews from users. This three-piece set includes a heavy vinyl tablecloth and two matching bench covers. Amazon.com also sells elasticized sets in different patterns. These sets fit benches up to 82 inches long.
Walmart sells similar items. However, the store also sells several outdoor bench cushions by the Mainstays brand. These cushions are made of poly fiber padding and polyester fabric. The cushions tie to picnic table benches.