I'm kicking around the idea of splurging on a new iPad (well, I've been kicking it around but it looks like I'll actually have the cash to do so soon). And am completely torn between doing a 16GB w/ 4G or a 32 with WiFi only. How much space is left after iOS is installed? Are you down to like 12? Or is it more reasonable? I don't have a smartphone and would love to do the 4G/GPS loveliness, but don't know how large iOS actually is. Any advice from fellow non-smartphoners?