In a large bowl, with electric mixer at low speed, combine sugar, butter, milk and vanilla.
Beat at medium speed 1 to 2 minutes, until creamy. If desired, add more milk until frosting is spreading consistency.
Peanut Butter Crunch
Substitute peanut butter for butter; sprinkle either candy peanut butter pieces or chopped peanuts over frosting.
Add 1/3 cup unsweetened cocoa powder, adding milk, a teaspoon at a time, until desired consistency. Top with chocolate curls, if desired.
Substitute fresh orange juice for milk, add 1 teaspoon orange extract and 1 teaspoon grated orange zest. Top with thin strips of orange zest.
Substitute fresh lemon juice for milk, add 1 teaspoon lemon extract and 1 teaspoon grated lemon zest. Top with thin strips of lemon zest.