For one of your table options grouping floating candle vases together is a pretty option for a non-floral centerpieces. To add the "wow", tint the water in some of the vases a dark purple and some a light purple and float gold candles.
DIY: Glitter Candle tutorial (using Mod Podge & glitter). What if we did this with baby food jars or something like that? It would hide the "fake" candles we have to use but be simply and pretty and add some pizazz & maybe some gold if you want.