There are many things that come to mind when I try and decide on an era, like personal hygiene practices for example, but probably one of the main things to consider is the fashion.
I love the 20's jargon, it is all the Bee's Knees and the Cat's Meow, and a really fun movie to show fashion, music, jargon & dancing of the 20's is Thoroughly Modern Millie.
I am not sure what is so appealing about gangsters but I do love a good gangster movie and even more so if it is funny. Oscar has great lines that my family like to quote, not to mention a huge cast. I especially love Tim Curry as Dr. Poole...
I have not read a lot of books that involve the 20's I am not a fan of The Great Gatsby although I did read it and see the movie (Robert Redford & the 20's of course I watched it).
I am already looking forward to picking my next era to explore.