Am I Blue?

I've been meaning to paint the walls of my living room for as long as I've owned my house. Other rooms have been painted various colors but the living room is still a boring white. At some point, I picked out a pacific blue that I've since decided is too dark for the space. I think I've settled on a light grayish blue from a poster that's hanging in the living room, but I haven't found a paint color that matches it. I might have to lug the picture over to the paint store to get an exact match because the tens of swatches I've brought home aren't even close.
Although I haven't quite picked the main color, I might use a second color (a darker blue from the poster?) on the wall with my fireplace and built-in shelves. I don't know how a two-toned room will look in real life, but they do that kind of stuff on design shows all the time.