Water/sewer is billed quarterly AFAIK, and there's not much you can do to lower it other than use less water. My bill has been around $115/quarter in a fully attached 3 bedroom with 2 adults and 2 children.
If you are in National Grid you should keep your gas with them. Be prepared for price fluctuations, but it's likely to cost you to fix it with an ESCO. If you are in ConEd gas it will depend on what price you can get. I have gotten good pricing for commercial customers, but do not know what its available for residential
Balanced billing is a totally different thing than fixed/variable rate. All it does is spread out your annual heating costs so that within each year (or maybe quarter, not 100% sure) you pay the same amount each month. But they adjust the next year/quarter's budget based on any actual differences, which means in the end you always pay for your actual usage no matter what.
@puddles, if you think that's helpful, go ahead. But it won't save you any money. My electric+gas average over the last 6 months has been $280/month. I'm still on ConEd variable supply for both. I assume I can do better than that, but I haven't had the chance to research it properly since I moved.