Light grey for groomsmen and darker grey for groom! I love the idea of the groomsmen in a different color suit than the groom! Only the groomsmen would have the dark gray ties and the groom the lighter.
you can get the vases at Dollar Tree, 3 bags of rocks and the floating candles in a 6 pack at Hob Lob. With a super gorgeous orchid as the flower, in the colors of the wedding, you've got yourself a very pretty, and very thrifty centerpiece!