Simple. To the point. And, most of all, cheap.
But the tables at my venue are really big, and one candle is really small. I considered floral collars, but wasn't really sold on anything until I visited with a florist and saw something similar to this:
She showed me four white candles in glass vases on a table, all different sizes, set among scattered red rose petals. It was really, really beautiful. And all this could be mine(!) for the bargain basement price of $55 per table! Well, plus tax. And plus delivery. Minus actually owning anything when I'm done, because it's all rented.
That just seemed ridiculous, so I went to work looking up candle-safe vases and pillars. There may be better deals out there, but I found three cylindrical glass vases (5"x12", 3.5"x10", and 3.25"x7.5"), and three ivory pillar candles (2.8"x8", 6", and 4") for about $27 per table, inclusive of tax and shipping. I estimate the rose petals at $5 per table (or less; since that is what the florist wanted to charge me, I bet I can get them myself for less money), putting my centerpieces at roughly 50% of the cost of the florist's identical centerpieces. Score!
So remaining items are to find a good source for fresh rose petals in the right color (and I haven't decided what color that is yet), and pick up a few more vases. My bridesmaids are scattered throughout a few tables, and I'd like to set one empty vase for each of them to set down their bouquets. Maybe I'll decorate the vase with a ribbon around it somewhere with each girl's name on it? I'm also planning to pick up some smaller ones to make centerpieces for the tall cocktail tables that will be set around the dance floor, which will give it a slightly different decorative feel than the dinner area.