The example you provide is ok, but it is not an example that shows all possible uses, so you should not think that to be going to is used only when something is planned.
Normally the form of to be going to is associated with the imminence of the action, aspect and modality - these are the terms that you might be referring to as "emotional meaning".
In your example, the to be going to is used because the actions are imminent. These explanations might sound complicated, but once you are comfortable with use this comes naturally and without thinking.
If you compare the two versions that you would have from the example provided
- I'm going to put you in our deluxe room with a kitchenette.
- I will put you in our deluxe room with a kitchenette.
to me the main difference is that in 2. I will means only in future (and therefore is less certain), while 1. I'm going to means some sort of imminent future (immediate, planned, unavoidable, etc; it can also imply resoluteness, firmness of decision). Therefore I am going to form expresses more certainty compared to I will.
However this opinion is due to the context of the example, non-verbal aspects, such as tone and attitude of the speaker, can modify these expression to the extent that would make them express exactly the same thing.
Try to go through the section on tense, aspect and modality implications in Wikipedia entry on future tense:
Am/is/are going to + VERB always, and will + VERB usually, imply not just futurity but also aspect (the way an action or state takes place in time) and/or modality (the attitude of the speaker toward the action or state). The precise interpretation must be based on the context. Specifically:
am/is/are going to + VERB sometimes implies intentional modality, as in I'm going to do that; but sometimes it does not, as in It's going to rain.
am/is/are going to + VERB always implies prospective aspect, combining the present focus in the main verb am/is/are going with the futurity of the second verb. Thus, for example, It's going to rain combines a present viewpoint of the situation with a description of the future. This feature is analogous to the retrospective aspect of the English present perfect have/has + VERB + -ed, in which past action is presented from the viewpoint of the present.
will + VERB can express aspect alone, without implying futurity: In He will make mistakes, won't he?, the reference is to a tendency in the past, present, and future and as such expresses habitual aspect.
will + VERB can express either of two types of modality alone, again without implying futurity: In That will be John at the door, there is an implication of present time and probabilistic mode, while You will do it right now implies obligatory mode.
will + VERB can express both intentional modality and futurity, as in I will do it.
will + VERB can express both conditional modality and futurity, as in: Don't sit on that rock—it'll fall!
will + VERB can express futurity without modality: The sun will die in a few billion years.