Yeah I'd reccomend Westchester over Fairfield if you want to keep the door-to-door commute under 45 minutes. Stamford is really the only affordable somewhat cheap(er) place in lower Fairfield and the trains from there take about 45. Greenwich and Cos Cob are somewhat closer but VERY pricey.
Probably the best train access from Westchester can be had in White Plains. There are express trains leaving the White Plains station ever 4-10 minutes during the morning rush hour. Another popular big town is New Rochelle. The rents are a little bit pricey in these areas, but you might be able to find something for $1,200. I think the rents in White Plains for a 1br probably average closer to $1,400 a month.
You should also consider looking into some of the areas in Eastern Yonkers that have stations along the Harlem Line (next to the Bronx River Parkway). In most of eastern Yonkers, which is pretty nice you can find a 1 br for $1,000 or less. Stay away from Western Yonkers though, as that area is pretty sketchy. The trains in eastern Yonkers take about 30-35 minutes to get into the city, but they run local instead of express for the most part, so they make a couple of stops.
There are also a lot of smaller towns in Westcher that you might want to look into. Places like Eastchester, Tarrytown, North White Plains, Valhalla and Hartsdale are all pretty nice. These towns are much more laid-back and "slower" than places like White Plains/New Rochell/Yonkers. The rents in these areas can vary from town to town.
If you want the best train access though, definitely look into White Plains. The express train takes 35 minutes to get into Grand Central.
Also check out this map as it is very helpful: http://www.nytimes.com/imagepages/20...N_GRAPHIC.html
. It shows the commuting times from all of the train stations in the NYC area.
Keep in mind that the trains from New Jersey and Long Island do not go to Grand Central (at least not year though. the LIRR is going to have access to Grand Central eventually, but that is a couple years away from actually happening).