All kinds of options. You could frost the windows, do Venetian blinds, roman shades, plantation shutters. Really depends on what kind of look you want.

The interior windows look like they're only 3.5 to 4 ft wide. Roman shades, or folding floor standing screens might work, especially if you seldom have company.

The folding screens could hide the exercise equipment on a daily basis....

HI -- Look at having loft windows put in . Very nice looking with the thin black framing . They could be center divided to open like a french window . When closed for privacy you could have drapes that close over . That would give that high space some interest too. Search " Loft windows " .

It sounds like you only need visual privacy, not audio privacy. I would install shutter style blinds, which aren't flat, but 3 dimensional. Get a valance for both sides of the headrail so it looks finished from the living room and loft.

I wouldn't recommend Roman shades because it only has one finished side.

If you need sound privacy for guests, I'd recommend drapes that can be closed and will absorb living room sounds from waking your guests.

HI -- If you do the search on Houzz you will see the first few photos up are some good ideas .