I currently live in NYC. It certainly has a lot of jobs, but it also has a lot of competition for those jobs. Is it the best place? For some people, yes. For others, no.
NYC is a great place for people who can handle a full time day job and also work smaller (example Showcase) shows on the side. There are thousands of small theater companies that are always looking for good help but cannot even come close to paying a living wage.
There are jobs that can pay a decent wage and a few jobs that pay a good wage. But lots of competition. Lots. And as the economy gets worse and worse, more qualified SMs will be willing to work for the "decent" wage instead of the "good" wage rather than not working at all.
There are also a lot of jobs that are considered a full time commitment but still don't pay what I would consider a livable wage. And yet, there is still a tremendous amount of competition for these jobs.
I have traveled a lot with jobs. Both with tours and with sit-down jobs in theaters outside the City.
The key to having a career in stage management is flexibilty. Be willing to travel, be willing to compromise (on money or time or duties), but also know your bottome line (on money or time or duties) and stick with it.
With the economy going the way it is, smaller companies will really begin to flourish, I think. As more expensive productions must close, there is room for lower budget theaters to get higher calibre employees and more audience.
It will be interesting to see what the next few years bring.