I am drafting plans for a fairly extensive addition. I'm working through designing the master bathroom which is on the second floor. I want a curbless shower, and plan to use shorter I-joists in the shower area to accommodate this. My decision now lies in exactly what parts of the bathroom subfloor should be dropped and by how much. I have up to 4" of potential drop available to work with here. The main bathroom floor will be within 1/4" of the rest of the house, which will be either LVT or hardwood (undecided at this point).

I have a few options in my head. The easiest is to leave the whole bathroom flat at one elevation, with the actual shower area dropped 2.5" to accommodate a slope starting at the partition wall:

Not any more difficult, but I could drop the shower bench area 1/2-3/4" and use a Schluter RENO-U profile at the entrance of the bench area:

More involved would be to have two plane changes, a ramp down to the bench area, then the primary slope to the drain. This puts the drain more like 3-3.5" below floor level.

I could probably find a way to slope all the way to the bench, but I was trying to keep the slopes simple since I want to use large format tile. I was hoping to not have a bunch of cuts to meet a complicated combination of slopes.

I want this bathroom to be very functional and perform well. I don't want to have issues with water splashing out of the shower and not draining. None of these options provide any or barely any slope to the area where the bench is located. What is your opinion on this design?

Happy to answer questions I may have omitted and would love to know your thoughts. Also open to other ideas.

PS: Here is what I have to work with on dropping the subfloor.