Hmmm, I appreciate your example Airwalkrr but when you say:
and make ANY hostile creature's attitude indifferent automatically.
This is not how it plays out ime.
The problem with using any social skill (except for the explicit combat applications of bluff & intimidate) is that their needs to be a dialogue occuring. If one side is not listening then a diplomacy +26 is not able to be used.
Sure, by RAW there is grounds for the above to not be true, but the quality of a game where hard RAW interpretations over-rule DM's game mastery is going to be pretty poor. Not that I think such a diplomatic Bard cannot prosper - it is just that this Bard needs to hunt for opportunities to engage in dialogue.
Anyway, back to the OP. To get the most out of diplomacy for your character, your character needs to:
- use it as often as possible on the most important npcs you can find
- it is a very inefficient gather information so don't waste your time trying to use it like that
- do the gather info first to pinpoint who manages what
- then go to the important people
- have a reasonably legitimate case first as something for the skill to expand on
- use the skill to get the assistance you're after
The assistance can be extra helpers, backing of the law, non-intervention, equipment, or even someone else will do something on your behalf + more. It all depends on campaign circumstances. Essentially you'll want to use diplomacy to build a social network and you'll want to reuse and expand it.
In a mechanics sense, diplomacy can be used to gain character advantages in a dialogue rich setting.