When planning your wedding reception, it is essential that you find a bartending service that has professional mixologists and know how to tend an open bar or a cash bar. Which one you have depends largely on what your budget will allow. Simply put, guests pay for their drinks for a cash bar, they do not when it is open. Some people cut costs by only having an open bar open for about three hours, or by opting to serving champagne, wine or beer. If you go with a cash bar, guests need to be aware. Many people only carry credit cards.