I have an 11" Air and an iPad Mini and love the combination.
But I can't do my work on the iPad alone so the MBA is important to me. But I do tend to use my Air at my desk attached to my monitor and keyboard a lot.
Depends. Do you need a COMPUTER on the go? If so, option A is your only option. If you do not need to work outside of your house then I would go with option B.