@Anna16135 The most important thing I would tell you is that you should NOT spend a ton of money on expensive sheets. Sheets are the most likely thing to need replacement when running an AirBnB, so expensive sheets can become a large operating cost if they need replacing on a regular basis- due to stains, mostly.
I use all cotton sheets and I buy from Amazon. They're about 400 thread count. I just looked at my order history, and California Design Den seems to be the brand I've purchased the most. They seem to hold up really well. I also use white sheets only, as they're easiest to deal with when removing stains. Kia