A smartphone is an intensely personal device. It’s hard to share one. So when giving a demo of mobile software, especially to a writer with trifocals (ahem), use a tablet instead.
This works especially well for iPhone apps. They’re actually readable from more than three inches away when run in 2x or “compatibility” mode on an iPad. If you really want your small app to shine on the bigger iPad screen, install RetinaPad (via Cydia). But it’s not completely necessary.