It will depend on a lot of factors (insulation, windows, efficiency of the furnace, etc.) but oil is always a lot more expensive than gas. So I would advise you to stay away from places with oil heat. I live in CT in a 1600 sq ft townhouse (new construction, well insulated, good windows) and the highest gas bill I had last winter was $109. This winter it was $102. Otherwise, under $100. Once the heat is off it's $17 per month (minimum service charge plus whatever is used for cooking).
ETA: I don't do budget billing, but electric plus gas average out to about $150 per month year round for me. Gas heat and stovetop/oven, gas fireplace used regularly, electric water heater. Very, very limited AC use. Heat is 60 at night and when I'm not at home, 65-68 otherwise.