With your well insulated house, you might consider one of the newer mini split heat pumps, Todd. The prices are great(you'd only need a small one), and they're an easy DIY install. All you really need is to get it tested and start it(they come pre-charged with gas). They require almost zero maintenance(clean the filter now and then).

I put ours in primarily for the heating efficiency. It works so well with a pellet stove keeping the air flowing, filling in when the stove goes out, etc.

But the few times we had some humidity, and Mary Ann was melting, the AC is much more welcome than I thought it would be. Truth is, we've had hotter and hotter summers since we moved here.