Where Should I set my thermostats for 2 story house

[tsdal300]

I have a 2 story home served by a 5 ton system down and a 4 ton system up. The first floor living is open all the way to the 2nd floor so the home is very open and I have 3 rooms upstairs. I have been playing with my stats and monitoring the kw usage and I would like to get several opinions. The return air for the downstairs unit pulls from the top of the stairs. I have tried setting the upstairs unit about 2 degrees above the downstairs and I have also done it the other way. Any opinions on this?
Thanks

[countryhick]

Set them where you feel comfortable...

[docholiday]

within reason

[blackwidow]

lol my thoughts exactly country hick...... If I am gonna pay a high a$$ power bill, well I am at least gonna be comfortable...weather its 68* or 78* doesnt matter to me...