We are in the middle of a basement refinishing, and the most difficult part was trying to figure out rooms/sections because of plumbing limitations and those darn beam posts! It took us awhile to configure the space, and we used a cheap/easy-to-learn CAD software program, which helped to visualize dimensions, fixtures, etc. We did move everything plumbing-related into one utility area (walled off) away from the occupied spaces. I agree with the comment about the noise of the sewage pump, so could you relocate that into the utility area?

Our pre-plumbed bathroom layout is small, and we didn't want to move plumbing, so we maximized space by using pocket doors (since the bathroom has two entrances) with same throughout the rest of the basement. To ensure light and brightness (we have a deck that blocks light), we used glass-paned pocket doors (we have several on our main level, so this continues that theme).

We designed the beam posts into walls (the bedroom closet became L shaped) so they wouldn't be so obvious. Because of the beam posts, we have a large bedroom and office area that is divided by a half-pony wall (the beam post is at the end of this wall, and we'll wrap it to resemble other pillars on our main level). We also had to keep one beam post in the main area just as you enter the basement (through a door), so we included it in a pony wall, and it will also be wrapped.

We addressed the big open space challenge by dividing the room into areas and setting those off by the ceiling height--the main area, bar, and bedroom have a standard-height ceiling, but the "gathering area" (as I'm calling it) has a bit of a dropped ceiling (contains the ducting). You could wrap the beam posts and use them to set off your different zoned areas (if you don't want to incorporate them into the design). Maybe build a half-wall between the two beam posts at the bottom of the stairs, to separate the future bar/gathering area from the family area, which will still let light from those windows in.

I'm assuming the toilet/shower drains are established. Do you need a tub? Could you build out the bathroom tub/shower space, or flip the tub 90 degrees (assuming you relocate the sewage pump), so you could add a (pocket) door to the bedroom, for privacy if someone is staying there and people are using other areas of the basement?

If you're going to have a sink/laundry tub for the future bar, be sure to plumb that now, and make sure you have a drain. We had to put our bar sink against a wall not originally considered so we could tap into an existing drain. Our design changed several times.

My last words of advice are to consider any projects you might want to do on the main level now, before closing in the basement ceiling. We've run internet cable to several rooms (so we can be hardwired from rooms other than our current office--COVID/WFH made us consider this!), installed a video (and a basement) doorbell and required wiring, run a new electric line/circuit to the second floor (for heated floors in our "after finishing the basement" master bath renovation), and we've installed a couple electrical plugs and wall sconces in different main-level rooms (including added two floor boxes). Once you enclose the basement ceiling, there's no going back!