:idea: *Ikaga desu ka? *is a question phrase that asks : _"Would you like...?" _
:idea: *Dochira ga yoroshii desu ka?* asks _"Which would you like, [this or that]?" _ or _Which do you prefer [this one or that one]?_
*Singuru rūmu ka daburu rūmu, __ikaga desu ka?__ *asks
_"__Would you like__ a single or a double room?"_
:arrow: This is a _*__Yes__ or __No__*_ question - and does not ask for a specific choice to be made.
On the other hand...
*Singuru rūmu to daburu rūmu to, __dochira ga yoroshii desu ka?__ *asks
_"__Which one would you like__, a single or a double room?"_ or
_"__Which do you prefer__, a single or a double room?"_
:arrow: This is clearly NOT a _*__Yes__ or __No__*_ question, but asks you to _*__choose between two items__*_.
So, *Dochira* is used to ask "which one" and only when there are two choices.
"Would you like a room?" is a _*__Yes__*_ or _*__No__*_ question, so the correct way to ask this in Japanese is *Heya wa ikaga desu ka?*
:idea: However, if you have a choice to offer, in this case, single room or double room, and the context suggests the client (Kenny) has decided he needs a room already - it is correct to ask:
*Singuru rūmu to daburu rūmu to, __dochira ga yoroshii desu ka?__ *
I hope this helped!
Soredewa, may you learning be enjoyable. Mata ne! :D