I would love to hear advice from anyone who has dealt with the problem of a hot upstairs in their house.

We have a two story house. We have central air, and like most houses, the thermostat is on the main floor. The problem is that, even with the AC running, and the main floor a pleasant temperature... the upstairs is a few degrees warmer, and is not so pleasant for sleeping.

We are trying to minimize the electrical bill, naturally, so we set the thermostat to 25c (77f), which is a perfectly comfortable temperature. Unfortunately, the temperature upstairs is at least 2c warmer (4f), which makes quite a difference to comfort.

Is there any way to make the furnace suck more air from the upstairs? Cold air returns don't generally come equipped with dampers. Would blocking the main floor returns really make a difference?

We have a vaulted entry way - it is about 8x16, and contains the main stairway, and opens onto the upstairs hallway. (the upstairs hall is really a balcony wrapping around this entryway. I was thinking about suspending a ceiling fan in that space to circulate the air. That is a big deal, though, and I really don't want to attempt it unless it is guaranteed to make a difference.

The basement is positively chilly. What I really need is to get that air to circulate up to the 2nd floor!

So that is our situation. If anyone out there has dealt with this in a successful way, please share your advice!