I feel like we are talking about this endlessly in the appreciation thread. But ya'll know I can't resist throwing my "brilliant" ideas out there.
So, I'd do something much like what a lot of people here are suggesting; Nightwing: Director of Spyral.
This basic setup is about as perfect as we're gonna get; DC doesn't have a "super spy" so its a niche Dick can own, "Grayson" set precedent for it, and Dick has the skills and the leadership ability to pull it off. And the fact that Dick doesn't naturally gravitate to the darker elements of spy work, and all the secret keeping and moral gray areas, provides internal conflict for him.
To the world at large, Dick Grayson is just another super rich trust fund kid trying to fill the hours in a day. He does extreme sports stunts for fun and/or charity, (like snowboarding) and occasionally hits the high life, but lives far more under the radar than Bruce Wayne. Typically the most interesting thing about Dick, as far as the paparazzi go, is his new relationship with Karen Starr, better known to us as Power Girl. To the heroic community, Nightwing is the protector of Bludhaven; he's a skilled, experienced, and respected hero. The "Nightwing seal of approval" carries serious weight (as Superman himself once said). But he's just another hero protecting a city and many heroes wonder why he's settled for something so common when he could be on the League (if only he'd say yes to their invites!) or doing something....bigger. If only they knew the truth! Because in reality, Nightwing is protecting the entire world from threats they don't even know about. Remember when the Justice League failed to stop that biological weapon from turning every person in the Western hemisphere into twisted mutants? No? Well, you have Nightwing and Spyral to thank for that. Or, you would thank them....if you had ever known you were in danger in the first place.
On the homefront, Bludhaven is a crapstick of a city. A former whaling town that never recovered from the end of whaling, Bludhaven has tried several different things to salvage its economy and all of them have failed. The city is full of run down, barely functioning casinos, IT firms, etc. Nearly half the buildings in town are empty and condemned. Bludhaven has been a lot of things over the years and you'd see a little bit of each version here, all mixed up with a solid amount of tarnish and corruption and rot. It's what Gotham would look like if Wayne Enterprises hadn't been there to save it. Blockbuster still runs the city as the local kingpin, and smuggling would be the serious threat in Bludhaven; exotic weapons of all kinds (biological, tech, alien, etc) flow through the docks like poison and you end up seeing everything from brainwashed, weaponized metas to self-aware computer viruses all passing through Bludhaven on their way to black market auctions. In this way, Bludhaven becomes a crossroads for the DCU, mirroring Dick's connections to the wider universe.
With regards to Spyral, I'd establish Bronze Tiger as Dick's second in command, and Tiger (the Spyral operative) would become a rogue agent hell bent on getting revenge against Dick for taking Spyral from him. Dick would take Bette "Flamebird" Kane as a sidekick (which wouldn't sit well with Kate Kane). If DC would let me, I'd also bring Babs in for her computer skills; she'd still operate publicly as Batgirl, but unknown to most people (including Bruce) she's now Oracle again too. And, if DC would let me, she'd bring the Birds of Prey along with her and they'd be one of Dick's primary strike teams. So in this way, we can see how a collection of books could grow around Nightwing's Spyral; Dick's own solo, a Birds of Prey title, and the Batgirl book could dip into this as much or as little as it wanted. The ties to Nightwing wouldn't have to be direct; these would be more like satellite titles more than additional Nightwing books. After all, in Charlie's Angels you never actually see Charlie, right?
Visually, Spyral has to have its own design aesthetic and I'm not afraid of stealing, so we're going to take a lot of the visual elements from Snyder's Heavy arc. Spyral uses militarized blimps (with the Nightwing logo in the spotlight instead of the Bat), and their combat teams use mech suits similar to the robot-bunny thing that Gordon wore, etc. It honors the ties to Gotham while re-purposing it for Dick's own ends, which seems fitting. And since the Batman books aren't really using any of that stuff anymore, there's no point in letting cool ideas collect dust.
Dick handles all kinds of threats personally; this is comics so Dick being the director of Spyral doesn't mean he's stuck behind a desk and a mountain of paperwork. He protects Bludhaven as his "secret identity" but spends most of his time traveling the globe, having sexy fun James Bond adventures. So to help him handle superhuman problems, he upgrades his costume. We're basically going to give him a suit with Batman Beyond capabilities. I knocked out a quick doodle a while back for what this suit could look like....though of course I'd want to leave it to the professionals to design for actual publication.
Nightwing McArthur.jpg
As for rogues.....I'll just copy-paste this bit from another thread.
Blockbuster, Lady Vic, Torque, Brutale, Roxy Rocket, Deathwing, Double Dare, Prankster, Riot, the Bomb Squad (Electrocutioner & Plastique), Doctor Phosphorous.
This feels like a solid lineup of city-level threats. We've got mob bosses, assassins, dark mirror killers, walking WMD's, thieves, anarchists, psychopaths, and one sexy rocket riding adrenaline junky who just wants a rush and loves stealing stuff so the cops will chase her.
Professor Pyg and the Circus of Strange, Raptor, Leviathan, Queen Bee & H.I.V.E., Katrina (Kathy) Webb-Kane, Atomic Skull, Checkmate (Max Lord & Brother Eye), the Wildebeest Society, Intergang.
Building on the super-spy motif of "Grayson" I think there's a real solid foundation for Nightwing's more high-risk, global threats. We've got several flavors of secret societies, spy cabals, terrorist organizations and murder houses, plus hyper-powered killer cyborg robots in the form of Brother Eye's OMAC units.
Flamebird & Nightwing.
The actual, for-realz Kryptonian gods. They might be drawn to earth because that's where the last vestige of Kryptonian culture and religion are (thanks, Clark) but when they find out two mortal earthlings are using their names, the gods decide that Dick Grayson and Bette Kane would make great hosts, and just like that Dick has a "Phoenix" level problem on his hands.