Well, it sounds like this may not fit into your ideas, but one concept I've always held dear was the idea of the "Modern Fantasy World" - basically, take 1 Standard Fantasy Setting
, throw Medieval Stasis
out the window, and advance by 1000 years or so until you get something like the modern era in a fantasy world.
It would be difficult to pull off without becoming at least somewhat parodic, which is why I've never done it, but it would
make a good, and unique, way to combine a modern-day Slice of Life
story and traditional fantasy tropes. Action-adventure should follow naturally. Perhaps it could be set in a fantasy Earth or close parallel to save on world-building...?
Just throwing out ideas here.