I would like a multiversity series that expands on live action adaptation of DCs multiverse. One that goes in and out of each earth with each episode or revolves around at least 2 or 3 for each season. It would be great to see how they adapt characters like captain carrot, aquagirl, Quantum Superman Captain Atom.
Also, a great idea for a spin off series of this would be dark multiverse - in which they can do a dark knights metal sort of thing and make it like a horror-thriller type series. Since every earth in dark multiverse will collapse at some point.