To fix that last sentence there: We've seen Bruce and Cass, and (sadly, in Beechan's case, Dick and Cass) but I'd be so fascinated to see a take on their actual characters that was actual interaction versus straw men and needless bickering as a substitute for character study lame plot progression.
And now I'm wondering where (if anywhere) we've seen Cass and Dick interact at all, outside that series (Thanks for borrowing Dick, Beechan!) and on issue of Bruce Wayne: Fugitive. Where they basically smiled at each other across a room.
I do think a lot of it comes down to where DC is willing to let a given character show up. I've almost come to the conclusion that it may be better if characters don't have their own book, but can jump in and out at will. But that's probably just crazy talk. As I'm not sure they have a set book of character info that goes with any of the characters beyond the Trinity plus Dick. And, as we've seen (again, in BG series 2, as only one of what are probably many examples) even that probably isn't true.
Which brings us back to Tomasi. Who, I'm pretty sure, did have a book of traits and goals and lists and lists for Dick, a few for Tim and Bruce. It seems to show and I love it.
Now if we could only get one or two other Bats on somebody's list? Could we get consistent characterization? I don't know, and probably not of this exceptional level of characterization, but I'd love to see how it played out if we could.