Inexpensive craft store frames fit perfectly around light switch covers! --I like the LOOK Expensive (but not really BE expensive! -- 31 Easy DIY Upgrades That Will Make Your Home Look More Expensive--
Sometimes a switch plate is best when painted to blend with a wall. And sometimes a room gets a lift if you make one stand out: Cover with extra-wide ribbon, wallpaper, sheet music, or map of a favorite place.