I answered your question on the "crafts" board, but thought you'd see it here quicker.
I had a thought about the centerpieces...since you're doing bright colors and it's outdoors, how about using small fruits, such as limes, lemons and those tiny orange thingies (can't remember the name). I found a pic of what I mean. You could mod-podge the pic, onto the center of the vase, then you can see the fruit on top and bottom of the pic. Does that make sense?
Re: **Dani**