My apologies if this topic was brought up before, I'm attending university soon so I'll need a notebook. This will be my primary and only laptop, and hopefully it could be staying with me in 3 years of university.
The MBA has an excellent battery life and is very portable, thus easy to carry around in campus, but I don't know if 1440x900 will suffice in the long term. I do some gaming in my pastime, so I expect my notebook to be able to deliver 30-40 fps running on med settings (Dota 2, Skyrim, Diablo 3, Starcraft 2 etc.) I've read that the rMBP will come with Iris Pro 5200 on top of the obviously superior screen, but I'll have to put an extra $400 for that.
Also, which upgrades will I need?
256 SSD?
core i7?
8GB RAM?
I don't run virtualisation; all I do will be typing for assignments, watching videos, storing music & photos and do some gaming.
I know that others may disagree with me here. But I don't think the MBA is the best personal computer solution out there. I think the 13" MBP (now retina MBP) is the best overall solution. For your particular situation, I would encourage the 13" rMBP even more.
1) You stated very knowledgeably yourself that you might not be okay with the MBA's resolution down the line. The MBA's are questionably going to be upgraded to retina within the next few years (sooner than later?), so right now you may think it is "okay" with a lower resolution. But what about in a year or two, or three...eh. Especially if the MBA's get retina next year, then you might feel kinda crappy about it. Plus to be honest the MBA's resolution is just alright right now. People were using 1080p even before the retina MBP's came out, so MBA's resolution has been stale (at least to my mind) for a while now. Let alone another 3 years might now make you extremely happy.
2) Performance. Sure, there are going to be a few people below saying the MBA will have more than enough power and all that, but you can say that about most things. Just because a MBA has more than enough power, doesn't mean the rMBP would not do those things better.
3) Retina screen looks great
4) 13" form factor/size/weight is perfect for getting around campus. I've walked around campus plenty with the current 13" mbp and also my 15" sony and can tell you that you'll be happy with the update (likely a bit lighter and thinner, obviously), but even the existing ones are great for mobility.
Side note: Games should run fine, but I wouldn't expect to run skyrim on anything above medium, and probably a bumped down resolution from 1080p.
Lots of people are going to say you'll want 8gig ram, but unless you're doing actual work on your laptop, you don't need it. I have 4gig on my older laptop and have never needed more, for casual use (lots of games). i7 you can justify yourself. Storage you can justify yourself.
Btw I think you either mixed up a couple things or are misinformed. The 13" rMBP should get 5100 Iris chip, the 15" rMBP will likely get 5200 Iris "Pro" chip.
For justifying the price. It's a decent amount of money more, but I think it's worth it for the screen, more convenient power, and imo, I think the MBA looks a little fragile. Not from build quality, but looks a bit feminine to me. I'd prefer a more solid looking comp, so imho I'd easily justify the $400 jump
