Combine cranberry and lime juices, tequila, triple sec and simple syrup in a large liquid measuring cup. Stir well to combine. Serve over ice in glasses rimmed with coarse sugar or salt, if desired.
*In a small saucepan, combine equal parts sugar and water. (I usually use 1 cup water and 1 cup sugar, and keep on hand in the fridge for use in beverages.) Cook over medium-high heat, stirring, until sugar dissolves completely. Transfer to a heat-proof pitcher and refrigerate until well chilled, about 30 minutes before use in a drink. Store in an airtight container in the refrigerator up to 2 months.