Well it's likely Elijah and Dom will know each other from Untapped Potential so I'm cool with saying that they're on good terms and possibly friends (provided Dom doesn't talk The Path at him)
And I don't really have any characters that actually work at a club as Jesse works security at Midnight and Cameron is a performer but Midnight isn't classed as a club, but if he frequents that then he's likely to have run into Jesse or seen Cameron perform.
Gabe is still recovering from his turning but was a personal trainer and will probably be going back to that.
Roman and Rhys both fight as regulars at Tooth and Nail.