If you are wanting something more abstract, ask around for trees with unique branches.
For a winter party, spray paint the branches white or silver, cover with glue and sprinkle with epsom sale, rock salt and glitter. Ornaments and snowflakes dripping from the branches would sure set the mood.
If your party is more elegant, drape strands of faux crystals from red, silver, white or black branches.
Glue matching flowers onto the branches, or sprinkle artificial leaves onto them.
Experiment with different vases/urns and vase fillers. If using glass vases, try glass beads, dirt/moss, faux snow, or rocks.
It's good to add multiple heights in centerpieces for dimension and eye-appeal. Try pairing this centerpiece with a low one made from a slab of branch or tree trunk topped with candles, pinecones, acorns, ribbon, etc. Another low centerpiece idea is to use a long chunk of branch laying on the table surrounded with candles (or with holes drilled in the top for the candles to sit in).
This could be used for a party or shower that have themes like birds-nesting, enchanted forest, camping-outdoors, or for any season party.