Night Riding With Heavy Traffic
When winter arrives and brings shorter days, I add additional lights.  As you say, this is just more urban lights, but a bike light--especially if it is blinking--does make you more visible.  I prefer a light with an erratic blink pattern, such as Planet Bike's BLAZE with superflash mode (http://ecom1.planetbike.com/3047.html).  This erratic pattern forces you to the forefront of attention.

Lights and reflectors are essential but are not the whole answer.  I ride at night to be right where the motorists can see me.  It is always important to do this, but more so at night.  When there is no bike lane and no wide shoulder, I take the MIDDLE of the lane.  This is particularly important in an urban setting like Oakland or Sacramento, CA--where I ride.  Traffic in the city is heavy and often not much faster than I am.  Often cars are maxxing out at 25mph whereas I'm riding at around 15-18mph.  I can ride in the middle of the lane and if they're anxious, they can pass me.  The downside of this is that I hear a few drivers sounding their horns in protest.  The upside is that no one is surprised by me.  

No driver wants to damage their $20,000+ automobile by hitting a cyclist.  I'm a big guy, too--I'd damage their car.  So I ride right where they see me.  

Most places where I ride are urban city streets--usually with two lanes in each direction, sometimes a left-turn lane.  I use all of these just as a motorist would--and California state law supports me in doing this.  My goal and the goal of the law here are to be visible and predictable.  I ride like I belong there--without trying to be a jerk about it.  The motorists have a passing lane to get around me--and if they don't, I let them pass whenever it's safe and with easily-recognizable hand signals.  If they're right behind you, after all, you have their attention.  

Be both visible AND predictable.  

Have good situational awareness--know what's going on all around--and react to motorists who may not be doing the same.  

Have a safe ride!