Ok lets see I have an Ipad, Iphone, and MBP. I'm a family of 4, a teenager, a 9yr old and the wife.
Heres the useages:
Iphone - the wife and I use them as texters and callers, the internet features when out and about.
ipad - watching netflix and web surfing when lounging in bed, couch, backyard, at meetings.
Laptop - for doing work etc, childrens home work (book reports etc).