It's kind of driven by your i-tunes usage. I got 64 and that's overkill. But 16 might have been too little.

I plan on not upgrading for a while, and wanted to be sure it would last me - but yeah, 64 isn't needed.

A work phone's requirement is driven by i-tunes usage?

Seems odd to me. I don't have an iAnything but I find my smartphone's memory taken up mostly with jobsite pictures, large pdf files of construction drawing sets, etc. I've only got 16gig and I'm constantly having to remove files I'm not using any more to make room for new jobs.

xtn