The big advantage of cash envelopes is that, if you budget properly, you will always have the cash to pay a bill when it comes due. No more worrying about where the money will come from, be it for mortgage or rent, utilities, car payments, repairs, taxes, discretionary spending, etc.
At the top of any wedding budget worksheet you have the 6 most important categories: the wedding gown, bride's accessories, hair & make_up, groom's attire, groom's accessories and the wedding bands. These are the things that should always be budgeted first. After that, you have the following categories: the ceremony rental, the reception rental and equipment, celebrant's fees and flowers. Once you have budgeted money for these categories of expenses, you've got all the necessary things to get married. But of course, you have to accommodate the guests better than that.