Mostly, I use my iPhone for phone calls and email/texting while on the go. My iPhone is the "house phone" as we don't use a landline anymore. In use maybe 2-3 hours per day average.
On the go, I sometimes make use of various apps for spontaneous research, sports scores, and, especially recently, area gas prices
At home, I use the iPad for most things, especially evenings and weekends, including email. I love how integrated the iPhone and iPad are.