Earlier this year a fellow named Ryan Dancey suggested that d20 has four distinct quartiles of play:
Levels 1-5: Gritty fantasy
Levels 6-10: Heroic fantasy
Levels 11-15: Wuxia
Levels 16-20: Superheroes
There’s been some great discussion at EN World and elsewhere about how to define those quartiles, and how each group eventually finds the quartiles that suit them best.
My Eberron Campaign is slated to end around levels 14 to 16. I guess that's just on the fringe of when "superheroic fantasy" kicks in. Never really thought much about specific powerbands in 3.5 D&D, just knew that around level 16 it started to breakdown.