Painting - painting curved walls and ceiling

I want to paint my living room, but the walls and ceiling do not form a corner--they are curved. Any suggestions on how to decide where to stop the ceiling color and start the wall color? Can I make them into a corner?

Depending upon the contrast between colors, the two can have an effect on how large the room feels. In other words, how much ceiling runs down onto the walls or how much wall runs up onto the ceiling can make the room feel larger or smaller than it actually is.

I would start with the ceiling color at the point that the wall starts to curve. But it will eventually be your call.

In one room I started the wall from the bottom of the curve, in another I started it from the top of the curve, and in another I did the one wall the same as the ceiling, so I had 3 walls blue, and the ceiling and 4th wall white...In order of what I think looks best are:
1) From the start of the curve in the celing (more wall, less ceiling)
2) The ceiling and wall the same color
3) From the bottom of the curve (more ceiling less wall)


Something to consider is that I like the color better in the first choice so it may have something to do with it.


*Edit*
What you could do is paint the ceiling and adjoining wall the same color first, paint the other walls next. If you don't like it that way, paint the 4th wall again up to the bottom of the curve, and finally to the top of the curve if you don't like that. A little extra work, but I'd rather do the extra coat than be stuck with something you don't like.