Great for centerpieces. Float in clear glass bowls and vases (see all the floating candle bowls) with either crystal fibers or colorfill vase filler if you want something that fills the bowl but doesn't just sink or float to the top. You can then add a submersible floralyte if you want to add more color to the centerpiece.
Also see vase gems, beach glass & stones and shells
Place a mirror underneath for more effect.
If you are going to float your candles in cylinder vases allow at least 1/2" or more for the vase wall measurement . Most cylinder vases are measured by the outside diameter. A 3" candle needs a 3-1/2" diameter cylinder vase.Use a large martini glass as a centerpiece and float several different size candles in it.The photo shows the grande martini glass.