You could always come home to the Bay Area where the high in SF today is 60 degrees! You'll need heaters not air conditioning.
Air conditioning does help, but a lot of places are keeping their temps set at 78 these days so once you're over the initial relief going from outdoors into air conditioning, it still can be rather warm indoors if you're very active.
August is just not the best time to visit many of the states and also avoid hot weather. Your first instinct was right, to head to the mountains. Unfortunately, Denver won't be very hospitable for tourism during the convention week.
Another area you might consider is Tennessee and the Blue Ridge Mountains in the eastern portion of the state. It would be similar in climate and activity as that of the parks around Denver. My elderly but active dad and his wife went there in the summer for their honeymoon when they married about 20 years ago and enjoyed the scenery and activities, especially
Smoky Mountain National Park. You also have
Memphis and the home of blues, gosphel and rock and roll music with Elvis' Graceland.
Weather:
June through August: Summer in the Smokies means heat, haze, and humidity. Afternoon showers and thunderstorms are common. Temperatures increase through the period with July and August afternoon highs in the 90s in the lower elevations. Evening lows are usually comfortable with readings in the 60s and 70s. In the higher elevations, the weather is much more pleasant. On Mount Le Conte (6,593' elevation), no temperature above 80 degrees has ever been recorded.
Memphis has a humid subtropical climate, with four distinct seasons. The average high and low in July are 92°F (33°C) and 73°F (23°C), with high levels of humidity due to moisture encroaching from the Gulf of Mexico. Afternoon thunderstorms are frequent during some summers, but usually brief, lasting no longer than an hour.
And
Nashville, the state capital and home to country music and the Grand Ol Oprey.
Websites of interest for Tennessee:
http://en.wikipedia.org/wiki/Tennessee
http://www.tnvacation.com/
http://www.nps.gov/grsm/