Floral arch - As we're getting married outside, on the garden, I thought would be nice to have something to be the "altar". Depends on the cost of everything, I rather the floral arch than the lavender aisle
Wedding archway, included with ceremony! (pillars are a rental item)
El lazo de boda: I love the lazo de boda. It's a Hispanic tradition. It's the tying of a rope (in the Infinity or figure 8 shape) around a couple after their vows are said. A prayer/blessing is then said. It represents the everlasting bonds unity of marriage (two becoming one) as well as the forever love (infinity shape) you'll have for each other. http://en.m.wikipedia.org/wiki/Wedding_cord I did it at my wedding and it was truly my favorite part of the ceremony.
I really like the idea of a tree planting ceremony instead of the boring old unity candle. The couple waters the tree, then takes it home and plants in their yard. Just as the plant grows, so too will their love grow with time. Either dirt or water.