My living room needs more ambient light and I'm reluctant to drill holes in my ceiling. What are my options?
A standing floor lamp that emits light up will reflect light off the ceiling and create ambient illumination. However, it won't be connected to a wall light switch (unless you have or wire a switched outlet). I actually prefer standing lamps to overhead lights, since overhead lights can create harsh shadows (especially if there's just one bright one in the center of the ceiling).

As for the brightness: I like to use bulbs in the 400 to 1000 lumen range ("40 watt" to "60 watt" incandescent equivalent, if you're stuck in the 19th century mindset). I personally find anything brighter than that to be unnecessary—I'd rather have more lights than brighter lights. But that's really an interior decoration / preference question.