I didn't notice you were from Kingston...when you said "YYZ" I assumed you were in the Toronto area.

I wouldn't pay $664 to fly to Atlanta and Boston/New York, but that's just me.

You can replace my suggestion for a BUF-LGA ticket with one from YYZ on HP (America West). They're currently offering a fare of CAD$151 plus tax. Combine that with an LGA-ATL ticket on AirTran, and you're looking at around CAD$400 plus tax.

AirTran is a good airline to fly. I would take them over Delta.