If you need a hotel in a spanish-speaking country and need to ask if there is any room available you must say:

'Hay alguna habitacion libre?'
(Is there any room available?)


If you want to know the price of the room for a single or double room then you have to say:

Cuanto cuesta una habitacion sencilla / doble?
(How much does it cost a single / double room?)

If the recepcionist ask you how long are you going to stay you must answer:

Recepcionist: Cuanto tiempo se quedara?
Answer: Me (quedare una/dos/tres) noches
(I will stay for one/two/three nights)