Choose your base color, I recommend either red or blue. Purchase red or blue light bulbs and change out most of the white ones in the space. You may not wish to change all of them out however, depending on your preference for light in the area. Add alot of white Christmas lights wrapped around posts and gathered in vases. You can take it over the top by wrapping red or blue cellophane around the posts on top of the white lights.
Add some white flokati rugs, zebra print throws, and shag pillows. Use silver accents for a hip lounge, and lava lamps, beads, and psychedelia for a retro theme.
In either case, your feature drink MUST be the Martini! Consider also a Cosmopolitan if red is your feature color, a Blue Martini (blue curacao and gin) if blue is your color of choice. How great would a Martini Bar be? Create martini glass invitations to send out to set the tone ahead of time.
For music, go with some techno-dance or adult alternative for your urban theme, some psychedelic rock for a retro affair. Below are a couple of suggestions...
For an Urban Lounge...
For a Retro Theme...
