It would be interesting to find out how many of the 64G 3G+Wifi owners also have an iPhone. That's paying twice for data...once for iPhone and again for iPad.
I have unlimited data for my 32G iPhone, so I went with the 16G Wifi only iPad. If I need a connection and there's no free wifi, I just use my phone instead. (AT&T, so no tethering and I won't jailbreak either the iPhone or iPad to get tethering)