I'm using very inexpensive, yet surprisingly good-looking LED light posts from We_Honest (and others) from China, available on eBay. They are straight LED's without resistors, so you can't just hook them up to your accessory output - you need to add resistance.
However, one of the challenges with these lights is that the wire connectors are a very fine gauge - maybe 30 AWG or so? Pretty difficult to work with - particularly after being threaded through the layout and working over your head under the layout. The goal is to speed up and minimize the time and effort connecting hundreds of wires under the layout.
My solution to this is to create a 'lighting bus'. This is simply a thin, narrow material using copper tap (or somethings bare copper wire) attached to both sides.
The resistors are added to one side (I'm using 470 ohm resistors - you can wire these lights in series with lower resistors, but its actually more work to connect these tiny wires than just attached each light separately to its own resistor).
Then these strips are hung or attached underneath the layout parrelel with the streets and the wires from the street lamps. Now its just a couple of quick taps with the soldering iron to soften up the solder and attach the wire tips and their bare wire leads. Voila! Done!In addition to street lights, having this wire bus also makes it easy to add lighted cars. As you can see in the below photo!
I'm working out from the Station area towards the Commercial district: Below is looking up the Avenue of the Liberation of Quinntopia towards the Commercial and Residential areas.
Piko Street passes under one side of the station and connects Avenue of the Liberation of Quinntopia towards Minitrix Avenue and then onto an end where it does a hard right and turns into Kato Avenue.
Next! More lights! Once the street lamps (and cars) are installed, then buildings can be placed.