Totally agree with CryoPenguin - the baseline stock model should be fine for your purposes. But if you really want to spend some extra money, here are some things you might consider:
1. Carrying case - padded and with extra pockets
3. External HD - for full system backup and Time Machine. USB 3 is amazingly fast now.
4. CD/DVD Burner - in your case probably not really needed but these are cheap.
5. iPad mini - absolutely the best toy ever invented by mankind.