This applies to common situations: eg replying to an RSVP, asking a girl out, denying a software feature request. There's usually a bunch of different nuances that can be applied conveying different levels of seriousness, familiarity, humour, etc.
What I want is a phrasebook for common situations, with a page or so of alternative phrasings for each.
These would ideally be taken from real conversations. Imagined conversations (even/especially as imagined by NTs) tend to be unrealistic -- one does not necessarilly understand how one does something that one does without thinking. Would require some work.