I have a 1300sq ft townhouse and here's a rough estimate of our monthly bills

Power (in summer with A/C) $160.00
Water/Sewer $60.00
Gas (in summer) $50.00
Cable $85.00

In winter months Gas & Power bills are pretty much reversed since we have gas heat. In Spring/Fall the amount is drastically reduced since we're not using either A/C or Heat very much.