Serrated knives are mainly for bread.  If you like to use a serrated knife and cut vertically into the cutting board, our suggestion is that you keep one cutting board just for that purpose (whether it is one of our plastic cutting boards, or someone else's wood board) , that way you can  keep the majority of your cutting boards looking great.  You should always use a sharp knife, you have more risk of cutting yourself with a dull knife, as you will inevitable push harder and run the risk of the knife slipping on the food.