I would be looking for a minimum capability of 300W for a room that size. Of course the actual light required depends on things such as the height of the room, colour of walls and fittings, flooring, etc, but you can always dim or put in lower wattage bulbs if needed. Thus your idea for 2 off 3*60 is on the right track.
Have you looked at the low voltage lighting tracks ? Not sure if any of the multiple 10watt jobs plug into these yet but I expect they will in due course.
It is also possible to run a cable to a second fitting by making a groove in the ceiling plasterboard and plastering over it as one would do with a wall.