With a few exceptions, if it costs less than $2,500 you can expense it. While a bed can be classified as an asset, since it doesn't become "a material part of" the rental structure, you can expense it.
An example of the other side of that would be a hot water heater. A new one cost on overage $800. But when installed it does become part of the plumbing system of the house and that makes it "a material part of" the structure.
A window A/C unit can be depreciated if desired. But it's not a material part of the structure since it can be easily removed from the window when the property is sold, and not included in the sale of that property. So a window A/C unit costing less than $2,500 can also be expensed if desired.