At least on some other forums I frequent, Bruce Gilden became the reference answer for 'what is street photography'. This tends to build a bit of machisimo - 'get within a few feet, hit them with a flash, if you aren't in peoples faces it isn't street photography'. This often goes along with 'everything most be totally in focus so you have to stop down., etc.
These shots have a place, but the they are just niche within street photography. Most of HCBs worth was with 50s as I recall, often with faster glass in case he was in a lower light situation. I'm sure many would attack his work as too far away, too blurry, too cropped and so forth.
I am not arguing that this is what people are saying here. In general though, I've found those with the strongest opinions tend to prefer more aggressive, invasive styles. Big surprise, right?
Instead of asking about focal length, I'd suggest looking at a lot of street photographs. Figure out which you like the most and see what focal length they were shot at. If there is a lot of consistency it may be worth giving that a shot yourself.