You can see all my devices in my signature.
I use my MacBook for in class note taking, and when I want to have a little more web access at home on the couch. I use my new iMac for writing music in Sibelius, typing up lab reports for class, and to reply to emails that need a large response. I also sync all my iOS devices to my iMac as well.
My iPad gets about 80% of my traffic at home. I use it in bed, on the couch while watching tv, and needless to say, in the toilet. 🙂 I use it for responding to emails, web surfing, YouTube, and iOS games.
My iPhone is my phone for emails when I'm at work, school, or in the car. I normally don't web surf on my phone unless I have no other device with me. I play games on it as well.
But I seriously think I use my MacBook less now that I use my iPad.