I noticed you mentioned your A\C just a heads up, For every SEER point you are looking at about 7% saving on your cooling costs. Dont get too hung up on name brands like Trane , Carrier , Lennox as in all things you are paying for the name. Carrier makes, Bryant, Payne, ICP.. Trane is also American Standard and I believe they may have purchased GE not too sure on that on any way you can get a good system without the name. With CPS credits , Manufacturer rebates and Tax credits it can help with some of the costs but you must go through a dealer for those. When I replace my Heat pump 3 yrs ago with a 16 seer 2 speed with a variable speed indoor fan coil I received a 3200.00 tax credit now its only 800.00 I think. I was able to run my system @ 72.0 degrees all summer long @ 180 a month so not too bad. Good Luck OH yea may want to check on Ridge Vents on your roof and Spray on Radiant Barrier I think thats what its called and Attic Solar powered fans.
"qui tacet consentire videtur,"
"he who is silent is understood to consent"