The size of your bill is going to be more determined by how big your a/c unit is compared to your house (is it big enough, etc- 4 ton or 5 ton) and how well your house is insulated. And somewhat by how old your unit is/how efficient.
If you have a big house but you only have a 3 or 4 ton unit then your unit will be running non-stop to keep your house cool.
I have a 5 ton unit and I keep mine set on 74 during the day in the summer and 72 at night because we like it a bit cooler at night.
In the winter (when our bill is the highest) we keep the heat set on 72 day and night.
Our house is insulated very well and we have a good brand name unit that is only one year old.
I have seen the threads where ppl discuss what they keep their units set on and some ppl keep it super cold in the house during winter and let it get very warm in the house during summer. I won't do that. I am not going to be uncomfortable in my house to save $40.
Now if you move into a very old house that is not insulated well, you have an old unit that is not big enough for the house and the unit runs 24/7 and you have a $500 electric bill, then I might consider changing the settings on the unit.
I would love to live someplace where central sir wasn't needed in a house. Sounds lovely.