Option 1 assuming this basement level is going to be shared by other people.

I like option 1 as the better of the two layouts. If the bedroom just for occasional guests. If not, you may want to try to work in a closet/clothing storage.

Definitely option 1, for above stated reasons. I’d also, if at all possible, include a window in the bathroom….it’ll feel a lot less basement-y.

I also think option 1 is best - not having to walk through a bathroom to access the sauna. Plus the location of the bathroom is better in option 1. I do wonder if you can switch the sink and toilet placement… sink first, then toilet, then tub.

The door into the bedroom should swing into the room.

I would definitely not put a sectional in front of a window.

Well, it’s unanimous and that’s so helpful! Option#1 it is. Thank you!

A sauna is a social space for friends and family so you want easy access. It's good to be part of a shower room (#2) so that bathers can quickly cool off with a cold shower after each round in the stove room but the toilet should be in a separate room (a WC) for privacy.

Some more on saunas here: https://localmile.org/trumpkins-intro-to-sauna/

Egress window should be in the bedroom area and not blocked by any furniture.

Option one. Walking across the TV area to go to the bathroom is not ideal.

A typical sauna session is 3 rounds of heating up in the sauna and cooling down, repeat.

Each time you exit the sauna you are typically dripping sweat. You do not want to then dry off with a towel but rather go directly to the shower or outside to a lake or plunge pool to cool off and rinse sweat and bacteria off. What will the flooring in the central area be that you'd be dripping sweat on? Do you want to be walking nude (I know Americans are uncomfortable with that) through there frequently?

I would do option 2. But put the toilet on the end in it's own WC with a pocket door and then do a partition wall next to the sink to provide some privacy to people there and in the shower.

Also, reverse the sofa & TV. That would allow you to better center the TV for people sitting on the sofa.