We went through a similar process and landed on an 11" MacBook Air for use on campus. Proposed a tablet for classroom use, but then quickly got into the functionality aspects - missing keyboard. Sure, bluetooth keyboards are an option, but another thing to drag around. At the time we thought about Surface, our daughter wanted to stay in the Mac ecosystem. Her older MacBook Pro stays in the apartment, and via Dropbox, all content stays synced up.
Rdubmu brings up an important point to consider. While Office 2011 has worked well overall so far, there have been a few classes that required her to use the campus lab computers (Windows and Excel for statistics and analytical capabilities that the Mac version did not have). That then brought up the quandry of "do we go for an Office 365 subscription, setup a Bootcamp or Parallels instance on the MacBook Pro and run Windows as a virtual machine with a fully functional and feature complete MS Office installation, or rely upon the computer lab?". Office and other app requirements may/may not be an issue depending upon major and course requirements. The free Pages, Keynote, and Numbers are in my view plenty capable; but some courses require advanced features or plug-ins that the Mac Office or OS X Office Suite don't provide. Now if Office 2015 (rumored) comes out, that may solve the feature gap or will have to go for one of the options noted above.
Now we did buy the 11" MBA fully loaded with the intent that it last for the full four years as an undergrad. So far that part of the plan has been working out quite well as it has plenty of horsepower, is solidly built, has great battery life to last all day on campus, a fully functional keyboard, USB connectivity, etc.
Another variant to consider is a smaller form factor Windows laptop that is light yet functional and powerful enough for required apps, easy to carry around campus; and then pair that back up with a docking station/monitor/keyboard/mouse setup in the dorm/apartment. iTunes and iCloud would work well in this case given there are Windows versions.