Consider table shape
The shape of your table will dictate where you place decorative objects on it . Circular tables have less options and cry out for central placements as you can see in the photos below . Use variety in shapes and more than one object to create greater interest. The objects you choose to display should also work well with the overall theme/style of the room.
With a circular table the trick is to use scale and variety to energize the display. The two urns are simple and elegant and their height is counter balanced by the visual weight of the circular bowl . Everything blends but it is still interesting because of the objects used.
You can never go astray by choosing calla lilies for a table. They are tall and elegant and the white goes with any decor. They look particularly pleasing in this room where their height directs the eye to the stairs and the shape of the vase seems to nestle into the curve of the stairs in the background.
You have more options with a rectangular table.
You can stretch out your arrangement along the table . This works because of the harmony created by the use of similar materials and interesting shapes. It's symmetrical without being boring.
Repetition of shapes and simplicity in colour works well no matter what style of table you have. You can never go wrong with white objects. Matching the scale of the objects to what is around them is important especially in this room where the lighting is large and hung so low . Another solution for this table would be something long and narrow with multiple objects in it.
In this room the table is part of a larger design on the back wall . I love how the off centre placement of the flowers integrates with the open book on the display shelf behind it. It isn't obvious right away and it's a happy moment when you discover it - thoughtful design at its best.
Displaying functional objects on your tabletop adds interest and also provides a place to store things. When you use tall objects like these candlesticks you can get away with the off centre placement of them but with the simple lines of this room I would use one or the other of these groupings- my preference is the candlesticks. While candlesticks are a traditional solution to table decorations, you can WOW by choosing interesting styles, mixing finishes and massing them together.
When you use multiples it is bet to keep at least one aspect the same and then use variety. In the shot about you have varying heights and shapes but they are all clear and the same colour candle is used. Less colour always produces a more sophisticated look. . You don't have to have this many but rectangular or circular massing of at least five works best.
Height works when you have clear candlestick groupings. Multiples can create a cluttered look if the variables are not controlled. These holders are so delicate it looks like the candles are hovering above the table. Keeping the candles to one hue and varying it is always an interesting statement.
Crate and Barrel via Live the fancy life
Metal and glass always look good together because of their sparkle especially when candles are lit.
Using a piece of mirror as a runner and placing candles on it is an inexpensive treatment that always look exceptional. You don't have to worry about safety and any melted wax scrapes off with a blade. One
You can never go wrong with fresh flowers but you can move your WOW factor from OK to fantastic by considering the container you use and kind and amount of flowers. I love tall flowers on a dining table but you have to consider the space between your light and the top of the floral arrangement.
The use of tall thin vases and a sparse arrangement of flowers works in this room. This is a trick I often use because it cuts down on the the number of flowers you have to buy.
Here's another variation on the theme above. The flowers you choose can come from your own garden too. I manage to always have something fresh at my summer house without a price tag attached to it.
Sparkle everywhere. This small room makes good use of the mirror at the end of the table. You actually get multiple arrangements of flowers!
Go for the unexpected as a table decoration. This arrangement is as interesting as the rest of the space it is part of.
Being an avid beachcomber I would have no difficulty finding interesting driftwood arrangements. This one mimics the lines of the artwork behind it. Simple but very effective.
Some tables are so sculptural they need nothing more added.