I like the idea of changing centerpieces - every few weeks or month or so. It adds interest and a refreshed point of view. Seasonal greens, branches, twigs in a glass vase adds an earthy look. A grouping of ceramics pieces on a decorative tray (for protection) looks lovely as does a single, large piece such as a bowl. Pay attention to proportion-if using small items, use more than 2 or 3 small items to show volume. Or, add perspective and feature a themed collection of different size pieces, but use fewer pieces in this case. Feature color, a specific or mixed theme, texture and then change it when you get bored.
If you truly want something to stay out for periods of time, it is always fun to do a greenery piece with candles intermixed. You can then add color to your greenery and change out your candles. Sometimes storage space becomes an issue, but if you are adding different small accents continually, it becomes more friendly and inviting!