I've got an open floor plan, too. I picked a swatch of golden mustard color and used the different variations on the swatch in different areas. That made it vary, but match, too. Also, some areas have more light than others so I was able to go lighter or darker as needed to enhance the effect. I like to change things around and do seasonal decorating. This color seems to blend or punch up almost anything else I put with it!

You may know this, but it took me a while to start doing it. Bring home your paint swatches and tape them to the wall. If you have adjacent rooms like this, bring home the same swatches for each wall that has different light. Eliminate what doesn't work and consider the others as "good guesses". After you feel you have two or three selected, buy a quart of each and paint a poster board with them. Then put the poster on your wall and check it out for at least a day (daylight and artificial light). At this point, you have a large enough sample to feel confident in your selection. The quart can be used in the paint job and the spares can be used for accent craft projects.

I agree with Connie's advice above, but I don't see your floor plan as that open as your living room is a defined space with a walkway to the dining room. I would treat them as seperate rooms, and go with things I like which is the key to having a home you love and are happy in.