The constant crisis storylines was getting old but the DCU was great. I always wanted to see something more personal. Instead of hundreds or thousands of characters, dozens or less, more crossovers between families and teams. With some of the more horrible things that happened toward the end of the DCU and the DCNU now being firmly in place, these kind of stories are impossible outside of fanfiction!.
I would love to see a Superman Family and Batman Family crossover. Robin and Superboy working together if the Robin is Daimian could be hilarous. Black Bat and Supergirl working together would be different.
A Team Arrow and Bat Family mini series would have been cool, with Tim Drake working with Mia Deardon in one issue, Damian stuck alone with Lian in one issue, Dick Grayson and Red Arrow in another issue, Jason Todd and Conner Hawke more arguring and fighting than working together to the point that a bad guy might even get away or capture them, the Black Canary along with Cassandra Cain and Stephanie Brown working well in another issue, and last but not least the original Batman Bruce Wayne and the original Green Arrow Oliver Queen teaming up.
All the former members of Young Justice accidentaly and temporarily reunited, working together with the younger members of the Justice Socitety the All-Star Squadron, would be awesome.
The Teen Titians or the former members of Young Justice working on a adventure in Gotham City, hanging out in the old Titan's Lair and driving Batman nuts, would be funny.
I would love to see Irey West, Damian Wayne, and Lian Harper working together as a new Young Justice, possibly joined by a revived and powered version of Donna Troy's kid Robert Long and a relevantly aged up version of Garth's kid Ceridian. With all the kids being so young not even teenagers, their worried parents or guardians the Flash, Batman, Red Arrow, Troia and Tempest would all be yelling at the kids and blaming each other. That would be very funny. All five original Teen Titans yelling at their kids for doing what they would have would be extremely ironic.
Alas I can only dream. These kinds of stories are just a wish list. In the DCU there is no Young Justice. The Superboy is a brand new character with very little in common with his counterpart except for surface details such as being a clone. Even before the reboot Lian was killed off. The original Teen Titians never hung out when they were thirteen at the Titans' Lair so is no Titans' Lair. Two or three of the original Titans don't even exist! No Donna Troy, no Wally West, and I'm not sure about Garth. Without Wally West there's no Irey West. Without Garth a.k.a. Tempest there is no Ceridian. Also the baby Ceridian was killed off before the reboot.