I would take the Air but the screen resolution is really low.
If there only was 11" rMBP...
Then just get the 13" rMBP with an ipad mini.
It just sounds like you're trying to justify to a bunch of strangers that you need to get a laptop and an ipad.
I dont know about you, but the non retina display on the 11" air is more than fine for browsing the web or watching movies casually on the couch or bed.
At the end of the day it is your $ and you can do whatever you want with it!