Some tips on selecting the right centerpiece for the wedding from Kim Valee:
Room Ornamentation
If you host your party in a castle style room with moldings and ornamentation, the room already makes a statement. You should not try to compete with the room. In a room like, minimalist elegance typically work best.
But if you rent a tent, you need lots of things to dress up the drab vinyl white finishes. I always recommend lanterns or if you can afford it, ceiling dropping floral arrangements so the eyes stop before the roof. And always plan a look with the walls because you can never predict the weather.
Room Scale
The height and the ground surface are the obvious elements. But never underestimate the power of lighting, patterns and colors on the perceived room scale. It is necessary to analyze the overall effects. For example, large and tall hanging chandeliers lower the room height mark.
If the walls feature bold patterns, low height centerpieces on the dining tables would not look out of place even if the room is vast and have 17 feet high ceiling.
Guests must see each others
When you are in doubt about the height of your centerpieces, ask the florist to prepare a sample. They test drive it with friends of different heights sitting at the table. As you can see on the top right picture, low centerpieces enable you to put the emphasis on hanging decorations.
Otherwise go for the tall bouquet on the smallest clear glass base that is possible. Like I told you earlier, medium height centerpieces would not work.
Creating movements
Each picture produces the illusion of movement in their own way. Repetitions force the eyes to jump to the next element. Playing with the heights is a successful tactic that is illustrated on the bottom picture.
The place cards station use the fireplace as a focal point to attract you. Beside the flowers, make sure they are enough decorative elements on your table to create an impact. On a rectangular table, repeating a sequence of two accessories bring refinement to the room. On a round table, you try to create the effects of circles inside a circle.
The elegance of single blooms
I personally prefer centerpieces done with one or two colors. Since you have multiple bouquets on a single room, I think monochromatic centerpieces produce a more sophisticated look than the multicolor centerpieces. You can play with textures to add dimensions. When in doubt, remember that calla lily flowers look amazing for any occasions.
Inspiration shots
I used the creations of a floral design studio specializing in floral event. Located in Rhode Island, Stoneblossom has established a solid reputation over the last decade by designing artful and lush arrangements.
If you wonder what it was, the bottom picture showed a Brazilian dessert table. Over 1000 mini-desserts were placed in gorgeous Brazilian silk blossoms, and arranged with plateaus of glass, orchids and calla lilies. That is what I call an ultimate luxury in events.

Source: http://blog.kimvallee.com/archive/2008/02/14/tips-on-how-to-select-a-centerpiece.aspx