The Derby is an LA legend. It is actually a supper club, although I have never eaten here. On Saturday night's there is live swing music and you will see people dressed up in swing clothes (less frequently today) and just plain old regular clothes.
They also offer Swing Lessons on Saturdays at about 7:30 for free.
A little history: In 1926 the film director Cecil B. De Mille came up with the idea and it was opened in 1929 as Willard's Chicken Inn. The dome shaped roof led to the current name of The Derby, but in between Willard's and today it was one of five Brown Derby's in LA.
Dress Code: Trendy clothes, but just about anything goes, as like most LA clubs.
Laid-back beach bar with great bartenders, great bar food & drinks at reasonable prices, sports on many televisions, internet juke box & trivia, karaoke or live music on Tuesday & Sunday nights, smoking permitted in back patio, and friendly folk from college age to their 50's.
Dress Code: No dress code. Sandals, shorts & t-shirts are acceptable.
Going for drinks at Jones. Swinging away at the Derby. Taking it easy and strolling down Colorado Blvd. in Pasadena or 3rd Street Promenade in Santa Monica. Clubbing at Q's or The Mayan or raving away afterhours at Giant. Doing some work/reading while sipping coffee at the Insomnia Cafe.
Jones definitely has a cooler vibe (better music, older crowd) than The Formosa Cafe, which is on the opposite street. The Derby = Swingers (the movie) -- enough said. I find that Q's is better during happy hour than when it's full-blown packed with clubbers (especially during Asian nights). Giant is just a circus to amuse yourself in; lots of room to explore. I heard you might catch people writing scripts or movie reviews at the Insomnia Cafe -- nice space for when you want to get out of the house and do some work.
It was in the movie Swingers, and that really bad duet you saw in the movie is really at this place on the weekends. The music is not really good (But, very amusing), the drinks aren't cheap, but it is great people watching.
Dress Code: casual, but people look pretty trendy here.