I am with Her Ladyship. Every single renewal-of-vows event I have gone to ended in divorce. Every one.
I think marriage starts out as a delightful romantic roller-coaster, but as it matures it becomes a completely different ride. I like the way a relationship mellows to a delightful crawl down a tree-shaded lane. There is more time to enjoy the trip. My theory is that couples who crave the rollercoaster have not ever settled in to the beauty that a long term relationship provides. The vow-renewal events I attended, at least from my point of view, were a pathetic attempt to revive the roller-coaster.