what about just opening up the top half and create a credenza or high top bar area? or a pony wall?

Removing a wall looks so easy on the home renovation shows, but it can be very complicated as in your case with your HVAC vent. The other things you're going to want to consider is if the wall is load bearing you'll need to hire a structural engineer, get permits, and have the work inspected to make sure it's up to code.

A couple of other factors to consider when taking down any wall is that if you don't do it properly, chances are the paint on your ceiling is going to peel, and that can turn into a nightmare as happened with us. We had half the paint in a 300 sq ft kitchen and dining room peel down to the original from 45 years ago. Every time we thought we had it all off, more would come lose. And then there's the issue with the flooring where the wall was. Are you going to redo your floors so it's all the same? Or do you have some of the original that can be scrapped in there? Either way, it's going to be a problem you need to address now before the walls down, and you don't have anything to put there.

Thanks flair - Do you think it would look weird opening it all up except for the HVAC area and then making that large column with some shelves or picutes? Or do you think its to off center?

We have not done the floor yet to the kitchen. We plan on tiling once the wall is down. We are going to hire someone to inspect and do the tear down and dry wall for us once we decide on what to do. I really want to open the entire wall, but moving the HVAC gets to expensive, so just trying to figure out the best design to open up this wall without looking to off center.

Talk to people in that field as I'm sure they've dealt with this before. The big problem with trying to modify an older home to have an open floor plan is that you run into things like this that become incredibly expensive to resolve. I'm wondering if you need that vent if the wall is down? Is there another vent in the living room? Could a vent be put in the floor?

For what it's worth, when we renovated our kitchen, we tried to figure out how to keep a wall down [we had to take it down to removed old flooring, and rebuild it] to open up the kitchen and dining room, but without it, we lost all our cabinet and counter space so we put it back up. Sometimes you have to make the best of what you've got--kind of like dressing your body if you don't have perfect figure :)

Is there a basement, and if so, is it finished, or upper floor? Do you want to open for circulation or for the openness?

There is a short wall to the right shown in your first picture. Maybe the return could be relocated there?

i like the picture i posted with the round door fame opening up the space, i think, the air return needs to not be high lighted by putting more stuff around it. keep it very simple.