I wish they would just make more Justice League Unlimited. I want more season-long story arcs written and animated by Timm & co. The Cadmus arc in season 2 of JLU was pretty much the best thing ever.
I'd like a TV show that's darker and more 'adult' like the DC Animated Movies have been but in season-long format. They can just stop trying with the live-action stuff since Marvel has so thoroughly outclassed them.