Run iPhone with network off, wifi on Most of my iPhone usage is data - Google Voice, WhatsApp and Twilio Client. These run just fine over WiFi, so most of the time the cell network is redundant. I've noticed also that connecting to the cell network runs down the battery considerably faster than running in Airplane Mode. 

Is there a way to run iPhone with the cell network off, but WiFi on? Besides disabling my contract, of course :)
When you turn on Airplane Mode, Wifi is going to indicate Off. All you have to do is tap on Wi-Fi and turn on Wi-Fi. That should enable Wi-Fi while the phone is on Airplane Mode.