Another method to light a room is to use halogen spotlights. IMO, in a model RR room they have their place and even can be great to highlight interesting spots on a layout - but they are expensive, need a heavy transformer, and they become extremely hot.
Now you can also buy LED replacements for these spot lamps. You get them in white (and also in color: red, green, blue, yellow). In the housing of a halogen spot bulb there is an array of 15 hi-intensity LEDs. They also use 2.5 Watts at 12 Volt - so you can take a normal model RR transformer to power them! :thumb: The cost (here in Europe) is about $15 for one "bulb".
However - there are disadvantages, too: The light is beamed away in a relatively narrow light cone, so it still works as a spotlight. I think, with these lamps it would be difficult to get an even lighting of a room, even with quite a bunch of these "bulbs". The first two pics show the difference in brightness when looked from the side or straight-on.
Still worse is the problem of the color. Like others have said before - incandescent lamps give a warm light, while these LEDs shed a cold bluish light which (at least for me) doesn't look good at all on a layout. (BTW - it's the same problem with white LEDs for loco headlights!)
In my third pic you see the cone of this cold light (almost violet) compared to normal daylight coming in through the window. Oh well, it's a matter of taste, I think.
But I hope, that these bulbs will be available soon in the 'golden white' version of LEDs. But for the moment this type of LED is still way too expensive!
Ron