Apple MacBook Pro 13-inch (Retina Display). It's not leather, but shouldn't it be? My current computer got me through my undergraduate work, but I don't think it's got the gusto to get me through my graduate work. If, and only if, you have a spare MacBook lying around, perhaps you could show me how well it fits in the bag!
Macbook Air. I've been really happy with my decision to go with the Air over the Macbook Pro. The latest line is definitely powerful enough to be a primary computer for users who don't need more processing power than you'd need to play or stream video smoothly.