Grant Morrison's story is the most intriguing one for me based on the title alone. Since its titled Detective # 26 I'm assuming its some kind of prequel to Detective # 27. So an early Batman story, just before he takes on "The Case of the Chemical Syndicate"? Anyway, Morrison's proven he's a great scholar of Batman's history, and he did a great job recontextualizing the old Golden Age and Silver Age stories, so I have faith he'll do a great job here.
The Generations story is something I've, funnily enough, imagined a lot of times...a story where Batman ends up in the body of his 1939 counterpart and has to navigate his way through the Golden Age world while figuring out how he got sent back. Hell, I almost feel like they reached into my mind and 'stole' this story...LOL. Its interesting though that this was part of the 5G timeline. This seems to suggest that they planned on restoring the Golden Age Batman through a kind of time-travel. Wonder if that was the plan for Superman too?