iPhones and iPads come with varying amounts of space available; iPads offer powers of two from 16G to 128G and the price difference between them offers a substantial amount of other software and services one could afford by saving money on hardware.

What space usage motivates the usage? If there's a 90% full iPad at any amount of storage, what does the bulk of the usage come from? (I'd imagine media like music, photo and video shooting, etc but would rather hear from experts with some experience) Perhaps this is just careful developers at work, but you can get a lot of apps and still see very little space being used so I don't see why I would need anything more than 16 GB with my level of experience.

I'm looking for people with experience running an iOS device at more than 75% full for several months to explain what they've learned and perhaps explain whether they can live with the devices they initially bought or how they would take their current experience to select a new device.