You'll want to go to Manfest and Tokyo Valentino. Manfest (sex club) is more late night, but has multiple slings, diverse but mainly younger crowd, with a lot of action. It had more sex here per hour--like back to back for over an hour, with different guys, when I first walked in the door, than anywhere in my life. Blackout Wednesday on the third Wednesday each month, is just crazy. Over half the guys that night are just naked. It's non-stop sex all over the place. There'll be 5 guys bent over in the dark room getting fucked, plus guys in all the slings, plus guys in these half room things that you can lay back and put your feet up thru rings, so you can close the door and just you ass and legs going up, are the only thing in the hallway. All kinds of play places.
Tokyo is an arcade that should just be called a sex club. Active 24 hours but especially around lunch, nights, and weekends. Multiple levels with beds (both in the open and in rooms, bondage apparatuses, lounge areas, dark room, and straight boys are not afraid to stop by to get head. I was there recently mid day on a Saturday and got 6 loads in about two hours. I ,would say these two are the best right now.
From what I understand, The Den is black only, so I'm not sure you qualify. Don't worry, other places have plenty of horny big dick black guys. I haven't been to Flex to judge it on a good night, but it's been swallowed up by Georgia Tech development with their fraternity row right across the highway--interesting surroundings offer lots of potential. When I was there, it was a little slow (but I still got some action).
Good Luck