As some of the PP's have said, I think tall centrepieces are fine if they are very tall, your guests will be able to see each other underneath them, its just if they are mid-height really that they will block peoples view.
I'm having 60cm lily vases, with a spray of flowers in them, we're doing these ourselves and did a mock up of them and tried putting them on our dining table and sitting on the chairs, we can see underneath them just fine.
I think candleabras can look brilliant and really have an impact,but I do think they lend themselves to a particular style and theme of wedding but if they fit in with yours then go for it, they're very classy and grand! Some wonderful pictures on google images.