I still find Batman a weird choice for a JLA leader. I haven't read much JL stuff, but in most stories, Batman is the loner, the guy who doesn't work well with a team. In Grant Morrison's JLA run, he even has files on how best to take out his teammates if they go evil. I just don't see a Batman (III) as a JL synergizer.
If anything, I'd try to find a way to fit the Watchtower in and have that give some synergy to a Justice League team. Maybe on a Martian Manhunter card, or even as a glyph?