I love your alternate sketch, but here's my idea from the infinite depths of my wisdom. Ok stop laughing now.

The big long bench, I'd angle and triangulate the kitchen. You want/need bench space. This will open your dinig area up.

Also, I'd want to differentiate the dining/lounge room, but your right you don't want a wall. Why not look at putting a feature pillar fireplace. Long rectangle. Something you can see through. It will define the room, but not box it in.