If you don't have a huge floral budget, or just aren't that interested in flowers, there are many way that you can use simple arrangements to make a big statement. Sometimes a beautiful vase with a single flower on a clean table, cocktail table, or coffee table can look amazing. On an escort table or buffet, create a row of the same simple vases for dramatic effect. If you want to go with a more simple vase, such as the glass one below, choose an interesting shape or etching and fill with a simple nosegay.
Choosing simple arrangements can help to emphasize a casual theme for your wedding. It will also bring down the cost of flowers and materials. Consider finding a flower market or wholesaler in your area and putting these simple arrangements together yourself. Even more sentimental, ask to use cuttings of flowers from the garden in your childhood home or from a place that is meaningful in your relationship (with permission of course!).