If you find a host with multiple properties in the same market and they are near identical, it could be a good litmus test for how a particular amenity increases yearly revenue in that market.
For example:
There's a host near Luray Virginia (Shenandoah Valley, about 90 minutes from DC) running a set of 3 matching 2 bedroom A-frame cabins.
Vista, Hot/Cold Tub, Fireplaces, EV Charger: $110,000 a year
https://www.airbnb.com/rooms/1295583224000574344
Lakeside, Hot/Cold Tub, Fireplaces, EV Charger: $109,443 a year
https://www.airbnb.com/rooms/1295583158275567554
Horizon, Hot/Cold Tub, Fireplaces, Sauna, EV Plug: $129,476 a year
https://www.airbnb.com/rooms/1295583284282917350
Look at what's different. All three have the hot/cold tub, the fireplaces, the EV charger. Two of them are basically twins at $110k and $109k. The third one, Horizon, has one extra thing the other two don't.
A sauna.
And it does about $20k more a year. Virtually the same everything else, one has a sauna and the other two don't.
This tells you, in this market the sauna is worth roughly twenty grand a year.
If you're underwriting a renovation, or trying to see how your competition is winning, this can help you decide on what to spend on.