The best thing for cats is a carpeted cat tower. Most cats love to perch high and it allows them to scratch either horizontally or vertically. Cats like to play and sleep on them too. They come in a variety of shapes, sizes, and colors. Put your cats on it and move both front legs to show them this is what they should be scratching. If they do it on their own, give them treats. Sprinkling ground catnip (no stems) on it helps some cats.