Flowers is one area that is easy-peasy to DIY. For my mother's wedding, e.g., we went into Elliot Bay, picked up a book on flower arranging, read the bit on boutonnieres/corsages, put it back down, and headed to Northwest Florists Supply to get cracking. (Unfortunately, you can't just toddle in with any borrowed business license now; you have to register, and only two people are allowed in the warehouse at a time.)
Anyway, here's my plan for centerpieces: FLOWERS FLOATING IN A BOWL. (I know! Are you okay? Maybe you should sit down.) This is, of course, a reference to my darling beloved Virginia Woolf's Mrs. Dalloway:
Sally went out, picked hollyhocks, dahlias—all sorts of flowers that had never been seen together—cut their heads off, and made them swim on the top of water in bowls. The effect was extraordinary… Indeed she did shock people.(Sally Seton is a floral modernist, or maybe just a modern florist.)
No need for the candles, I think; and instead of smooth bowls, I'd rather use my mother's cut glass Feather bowls, but we'll have to wait to see whether she allows it. Here colors become an issue; I'm thinking of blue (in case you couldn't tell from posts below) for the primary color, and there aren't many blue flowers. You've got your hydrangea, your delphinium, your iris, and your prickly thistle. All of these are very pretty, but they're certainly not my favorite flowers. And, of course, Bob only knows if they'll float in a bowl of water. Back to the drawing board.