I had to make the same decision. Got the 13" Air.
Light. SSD is super fast. And the high resolution (higher than the 13" Pro, keep in mind) lets me view we pages + word docs more comfortably side-by-side for writing papers.
All excellent points. While the MBP is an excellent computer, it can be a bit heavy to carry around (I had one and subsequently bought a MBA).
The 13" MBA has an excellent screen resolution, is fast and powerful (unless you are a gamer), and is extremely portable. It also has a better battery life than the 11".
Money is part of the issue, along with that I can't decide what I want... I have consider an ipad and keyboard and would probally go for it if the ipad3 where realeased soon
I don't recommend an iPad for college. One of the things you will be required to do at college is to write many, many papers and take plenty of notes; bearing that in mind, it makes sense to have a computer with a proper keyboard and full version of iOS.
I was in this exact same position where I needed something that was very portable but was plenty powerful for home use and to do everything itunes or iphoto. I got the 11" macbook air in August and don't regret not getting the MBP. I also have an external monitor when I have to write a lot of papers and stuff.
Good points, and my only query with the 11" (which is a stunning computer, and, as KonPhiPhi pointed out, is not a toy, but a fully equipped powerful computer which is fit for everything except gaming and perhaps, 'heavy lifting' such as editing videos), is the battery, and, also, the smallish screen which may become tiring if one has to work at it for hours at a time.
Unless I have missed something, nobody here seems to have mentioned battery life. I had an 11" Air for school purposes and, due to my schedule, battery life was a big issue for me. With Wifi and bluetooth running, you should expect a MAXIMUM of what Apple advertises, with real use extending to the 3-4 hour range. If you can fit your school work into that timeframe, or if your college has proper charging facilities, then the 11" Air sounds good. If not, the 13" Air/Pro would be better.
Fair point and well argued.
To the OP: Forget the MBP (too heavy) and the iPad (not what you need for college, though it looks and is cool). Go for one of the MBAs, and perhaps, try to future proof it. If finance is an issue, try the Apple refurbs; there are some excellent deals right now on MBAs.
Cheers and good luck