If you're involved in a business partnership and have leased a space and intend to open rock 'n' roll bar with a retro look, then you have some serious redecorating to do. You can't just put some Zeppelin or Skynyrd on the stereo and hope people will flock to the place. You don't have to turn the place into a modern day CBGB's, but you do need to do some changes. Here are the most important ones.
Bring In An Old Jukebox
Even if you're planning on having a dedicated stereo system, you should have a classic jukebox in the place. They add to the vibe of the establishment. During the day, when your place is more quiet and laid back, the afternoon customers can play songs on the jukebox, so make sure that, if you are getting a vintage jukebox (as opposed to a replica), it has been restored and is actually functional and not just decorative.
The walls should be decorated with band promo work. The easiest way to do this would be to get some large concert promo posters. You don't have to get authentic posters unless you want. If you are looking to decorate with only authentic stuff, you might also want to get some concert set-lists from collector sites and frame them up and hang them.
Vintage Rock T-Shirts For The Bartenders
Most importantly, you need to have a special dress code for the bartenders. A rock 'n' roll bar is not some hip lounge or Latin nightclub, so it's important that the bartenders dress like they belong. This means rock and roll attire. Men should wear t-shirts and women should wear either t-shirts or tank tops. While you might make do with regular t-shirts, a better idea would be to have a bunch of vintage rock t-shirts printed up. These shirts will have cool band logos and artwork.
If you don't want to spend time sourcing authentic t-shirts from vintage shops in the East Village or Soho (which can get super expensive), you can get reproduction vintage rock clothing online.
Some vintage bands to look for include Slayer, Pink Floyd, Iron Maiden The Stones, Misfits, and Guns n' Roses. You could throw in some tie dye tank tops for the ladies if your bar is leaning to the Phish and Grateful Dead crowd.
In addition to the vintage t-shirts, the men and women should both wear blue jeans, with or without holes.