DC Comics has a landmark two-month new series running, "Convergence," during April and May of 2015.
This series brings together all past "imaginary" stories, alternate universes and many "Elseworld" tales, as if they are all REAL.
From "Kingdom Come" and its Superman to many pre "52" universe stories, this is worth a look.
Some stories move slow, but it is a kick to see so many alternate characters abandoned, or only briefly used, returning.
The only other downside is that there isn't space to truly develop and explore these alternate characters and worlds.