I've actually started cleaning and packing away a lot of it since I'll be moving at the end of July and will need to have it all packed up and ready for the wedding anyway (and a lot was already packed away since I live with roommates and can't decorate my house with it yet), so there's not nearly as much around as there used to be. I tried to put together a sampling of what my centerpieces could look like while I was packing some away, just so you all know what I mean by "green glass centerpieces".
There will be much more varying heights once I have everything out. Like I said, these are just the "pieces" I was putting away at the time. I have many, many (many) tall vases to add in for some height. As you can see, I have all different colors of green glass, which is what pulls together my wedding colors of varying greens (not just one specific green) and black.
I saw a cool idea the other day on Something Green (love that site). Not sure I'll use it for my wedding, but adding a tray under pieces of glass for centerpieces or room decor? Genius. Simple, but genius.