dcward89: I would shim the kitchen ceiling joists down to the lr/dr height and level it before drywall. This will eliminate the need for the fake beam, make a smooth transition between the rooms, and your cabinet installer will love you especially if you're installing frameless cabinets to the kitchen ceiling.

Yes, designing a basement space around mechanicals causes much compromise. I believe our basement depth is very similar to yours - finished floor to ceiling is 89.5 with a 10" drop to accommodate the ducting which for ours runs throught the middle. I'm not certain I understand the "room to room" exchanger. Connected to the fireplace above but does it just "dump" warm air into the basement? If yes, why can't you simply install a vent in the ceiling or wall rather than encase the duct section. If it runs to another room on the main level and "radiates" heat into the basement, enclosing it will minimize the radiant heat. If you must enclose, can you install drywall at 45 degrees to create a tray ceiling effect? Might minimize the look of intrusion into the room. My preference would be to just enclose the ducting and if your hutch is planned to remain below, the soffit will not be an eyesore. Are you using 2 x 4's for strapping across the ductwork to create the box. If you change to 3/4" ply you'll pick-up 3/4". I personally would not build any soffits to "balance" the room unless you can create the tray ceiling effect and your windows create a problem doing that. Here's a link to our basement. We installed an electric fireplace for auxulary heat. Good luck with your build-out. Here is a link that might be useful: Basement Photos

What about a shallow cabinet? I have concrete beams running through my unit which had to be designed around. I had a very shallow cabinet built in front of one beam and it is functional. It isn't deep but does provide storage. On the other end of my cabinet run there is a column that also had to be dealt with. For that column they just clad it in the same wood as the rest of my cabinets. It is the same depth as the cabinets so that it is somewhat of an optical illusion because you don't notice it. I actually hadn't realized that my cabinets didn't extend to the wall on that end until I remembered there was a column at that end. I also had to build around a column in my bathroom so I couldn't extend the counter because it would have looked odd. In that room I built functional storage with shelving at counter level and above and a hamper built in below. Again it is functional and doesn't look odd at all.

Is that area directly over the shower? Have you tested the fan to confirm it’s actually drawing air out & not just ’running’? Maybe it needs cleaning etc. What’s above the spot - another floor or attic?