iZombie has filmed across from my apartment afew times.
As far as the main DC stuff goes, funny story. I was heading to meet some people after leaving work super late, but chose to walk past the stadium (which is used as STAR Labs in Flash, just with a different structure cg'd ontop). Anyways, I'm walking with my headphones on only to pass the set as they're filming Firestorm, Flash, and Arrow all fighting Reverse Flash. So... sorta got that whole thing spoiled for me lol. It's also how I found out Oliver was joining the League of Assassins.
But yeah, they also have filmed around my apartment, Arrow does a lot of chase sequences a block from where I work so you see cranes there alot. A friend of ours was saying she's passed by the guy who plays Merlyn by her apartment a few times.
It's weird
Also I'm friends with some people who have worked on Arrow/Flash to varying capacities. Most of them say the same thing - just about the whole cast is fucking sweet as hell, except for Stephen Amell who is a total prick. Their words though.