I am planning on picking up the 13" pro. I can order it right now, but I'm waiting a week or so to hear of any major technical defects in the machine (which shouldn't be the case since it's pretty much the same machine).
I also debated between the Pro and the Air this generation, but the increased performance that you get for sustained max usage of the cpu/gpu in the Pros is what pushed me over to the Pro. For games (including Diablo 3), this can make a difference, especially in extended playing sessions, and the additional boost in gpu performance I get will also make future expansion(s) of Diablo 3 more feasible.
I carry my current Macbook with me to work, but honestly, the actual traveling I do outside of my car with it is so minimal that the weight difference is negligible (I also thankfully, have a healthy lower back). The higher resolution is VERY tempting, but in the grand scheme of things, I would prefer the increased performance. If I really want that additional resolution, I can always buy an external monitor.
I can't blame those who pick the Air though, it really is the better choice for the majority of consumers out there. I personally think the 15" is overkill unless you need it for work, certain classes, certain hobbies, or you're a more serious gamer though (in which case, you really shouldn't be on a mac at all...). That is, as a college student.