Quote Originally Posted by flogger View Post
Venting is a must, that air needs to move. Also, they won't do any good if the humidity is above 50% or so.
We used a swamp cooler in our old place in Northglenn, it worked great.

The above comment is spot on- think of the air the same way you would a liquid-it has to flow and you control the temp of the areas of the house by cracking windows in given rooms and closing off other areas.
Some days I miss it.
Also ventilating the attic is going to help big time - get the hot air out of the attic and it is easy to cool the house.