Our lawyer recommended a Delaware S-corp, given that our idea is fairly pie-in-the-sky at the moment, and is setting us up as one.

One thing I didn't realize when researching these corp types: an S-corp converts to a C-corp automatically as soon as they take outside investment (outside investment = preferred shares. In theory, they can issue common and keep their S-election). There's no additional legal paperwork required, and no complicated reincorporation. That makes S-corps fairly attractive to businesses that might want to take outside investment if they take off, but have no idea if they're going to take off.