A few things to keep in mind:
- When you live the in the city, speed means nothing when you have stop for a red light every block.
- If the city has lots of potholes, go for wider mountain bike width tires, to help soak up the bumps.
- If your routes have no appreciable hills, you don't need tons of gears.
- If you plan on leaving the bike chained up outside, nice bikes are first to be stolen in the city. It's better to use a crappy old looking bike, and let the thief steal somebody else's nice new bike.
- If you lock it up outside, invest in good locks, and learn the best way to lock your bike up.
- Don't go crazy with the bike accessories. Don't leave anything on the bike that you don't mind being stolen.