Lots of grays have brown undertones. I'm having a hard time picturing your space and w/o a visual I'm pretty much useless, but from your description I would think that as long as you stay with a warm gray (e.g. brown gray or greige, versus a blue gray) you will still have a sense of flow.

I agree with avesmor...I wouldn't do a blue gray with it because I do think it won't flow like you want it to. I don't have an open floor plan in our house, but have many fairly separated rooms and still had to deal with using different colors in each since they are separate and still had to make it all flow. I picked one color, DB Gypsy Tan (I call it my anchor color) and it appears in the front porch entry, the formal living room, and in the stairways and foyers and I used colors that would coordiate with that to help it flow.

I agree it would be helpful if you could post some pics :)

I do have a fairly open floor plan and so I understand the challenges. What is sometimes helpful, is to pick an inspiration object in a neighboring room (like a pillow, or something similar) and bring that color into the next room. For example if you have a gray room with sprinkles of blue accents, maybe make the neighboring green with sprinkles of blue. I hope that made sense lol. It is not just the paint colors that need to flow...in other words it is the rest of your decor as well (furniture, fabrics, etc.)

I don't have any pictures of my house, but I do have these I can share:

http://highlandhomes.reachlocal.com/?scid=1693730&kw=2441168&pub_cr_id=4879268619

These pictures are of the model home. NOT my home, but my home is the exact same floorplan so these pictures may at least help with understanding the layout. I'm hesitant to post pictures because we don't have decoration up, and, none of our furniture works with our house. We are planning on replacing everythig slowly over time. We want to get all the paint colors chosen first though.

Well in that case advice #2 - don't choose your paint colors first. Choose the furniture you want for your space first. Then choose a paint color that works with the furniture.

Paint is cheaper, and comes in thousands & thousands more colors. Your furniture is much, much more limited and it's probably going to outlive your paint anyway.

Figure out your "vision" - the feel and/or style you want. Keep it in your head when you shop. When you find furniture you love, consider the other hardware in the room (flooring, architecture, etc.) and color will become a much easier choice.

I would love to get furniture first, but that just isn't going to happen. We are going to have to live with what we have for probably 2 more years. In the meantime, we wanted to get rid of the boring "builders paint" that we had. We've already painted everything but the master and the office so we are almost done, just stuck on what to paint those 2 rooms. We're keeping it neutral so it won't be hard to change something if we have to down the road.