It seems these days more people are looking for open floor plans vs traditional, closed off rooms. It's better for entertaining and just makes the spaces feel larger.
In most houses you can open up the floor plan by either cutting away the top half of the wall and putting in counter space or by completely tearing the wall away. You can even create large archways to give it a more open look.
What you have to determine is what walls are load-bearing. Meaning they carry the weight of the roof and or floors above.
You also have to know where any electrical wiring, plumbing or heating duct may run.
I really like the open floor plans better than the traditional closed off rooms. Unfortunately for me my house is traditional. However I do plan to open it up in the future and actually use my bedroom as a dining room once I don't require so many bedrooms for children!

I'd rather my kids live with me forever though so this may never happen lol.