looking for communities in NYC comuting distance

I'm starting a new job in downtown Manhattan in mid-January, and I need to locate a residence-type hotel where I can stay for a couple of months.

I'm hoping to find one far enough out of the city that it's less expensive (yeah, I know, dream on) but with a fairly straightforward commute on the train.

Is there anybody out there who can make some suggestions? Long Island? New Jersey? Connecticut?

Any advice will be gratefully appreciated.