If you're really set on the rMBP (it's really great), then go ahead and get that. It's definitely not as portable or easy to use in a classroom situation, but it won't be too bad. The 13'' Air, or the 11'' for that matter, is the ideal computer for a college student IMO. I'm about to be a sophomore in college and I had an 11'' Air along with a 15'' Pro during my freshman year. Although the Retina is lighter and easier to carry than the MBP I had at the time, it's still a lot harder to carry then the Air. I know it sounds silly because it's not that heavy, but you really do notice the difference. I never brought my 15'' Pro to class, I always brought my Air, but I wouldn't have died bringing my Pro. I think a reason I didn't as well is because I would much rather have something happen to my Air than my Pro.
If you're in love with the rMBP, though, go for it. You'll always regret it if you don't. If, however, you like the Air because it's cheaper and a lot easier to carry, you won't be disappointed there. Like I said, IMO the Air is the perfect college student laptop, but the Retina is fantastic.
If you're in love with the rMBP, though, go for it. You'll always regret it if you don't. If, however, you like the Air because it's cheaper and a lot easier to carry, you won't be disappointed there. Like I said, IMO the Air is the perfect college student laptop, but the Retina is fantastic.