Q: Ipad air or mini w/retina display

Your best bet is to visit an Apple Store (or any other retail store that has the Air on display for you to try) and get a hand-on feel for the Air. Yes, it's lighter and it's smaller as well (but screen size is identical) but some that have upgraded to it say it has a cheaper feel to it (less solid due to less mass).

Sometimes in a case like this, it's best to be your own judge because you'll get wildly differing opinions here (and elsewhere).

iPad mini Vs iPad 4 Vs iPad 2 – A Detailed Comparison

http://www.redmondpie.com/ipad-mini-vs-ipad-4-vs-ipad-2-a-detailed-comparison/

Chosing Between the iPad 4 and the iPad Mini

http://macmost.com/choosing-between-the-ipad-and-the-ipad-mini.html

16GB vs 32GB vs 64GB: Which new iPad storage capacity should you get?

http://www.imore.com/2012/03/08/16gb-32gb-64gb-ipad-capacity/

How much content will fit on my iPod or iPhone?

http://support.apple.com/kb/HT1867

How Much iPad Memory Do You Need?

http://ipad.about.com/od/iPad-Tutorials/a/How-Much-iPad-Memory-Do-You-Need.htm

 Cheers, Tom