I'd launch an All-Robins book; make Dick, Jason, Damian, and Steph a permanent team. The first issue they can celebrate Tim's Funeral.
A Flashpoint Bat-Universe book would be cool; I'd love to see Dick's adventures as Dr. Fate.
A Bat-Horror book, something like Batman Gothic, especially drawn by Klaus Jansen, rotating characters in the Family.
Bat-Pets. Ace, Titus, Bat-Cow, Alfred the Cat, Bat-Turkey. Fun stuff, like Lil' Gotham.
Ongoing Clayface title. Man-Bat joins Detective team.