Its a huge yes from me. Easy to "dress" for arrivals/photographs/marketing, something easy to put props round for a birthday/anniversary celebration (such as candles, champagne etc). People will go into the room and go wow. People will book the room just for it. Hardly anyone will actually use it, but for airbnb purposes that doesn't matter to you, its all about the sell/marketing opportunity.
For the odd people who do use it you will need some ventilation solution that isn't a noisy fan. You also need a suggestion of privacy - I used an old fashioned room screen, three panels, fabric-covered so they can have the illusion of privacy from the door. Oh and a good lock on the room door, again for the privacy feeling!
It does need to be paired with a great bathroom with a wonderful shower. And a door on the shower room!
If it is a free standing bath you need some solution for toiletries and a glass of wine, something that doesnt take up too much space and is beautiful, remember no one uses it they just want to think they can! We used a wooden plant-stand type affair which was pretty and had flowers on but you could perch your wine on it. We also had one of those wooden bath shelf things across the bath(like a tray thing) styled with a loofah and pretty soaps/bath bombs.
We had three of these room types and they were extremely popular despite their eye-watering price tag. Factor in too you need double the bath towels at least.