I've pretty much decided on an F80. Though I said that I'd get a sedan last time around as well, my kids really are outgrowing the convertible (rear leg room is less than E90/E92), and I need as much space as I can get for future expansion.
But, if Mercedes offers a C63 convertible in a few years, especially one with over 500hp, it is really going to be a major temptation.