Idaho...closer than you might think.
My wife and I were able to take a quick trip to the Sawtooth Mountains in July2011. We were originally going to go to Steens Mountain in southeast Oregon but were prevented from doing so because the mountain still had an incredible amount of snow on it and the road to the summit was still unopened.
Disappointed, we shifted gears and headed to the Sawtooths, which we were surprised to find was a lot closer than we would have thought. We were not to be disappointed a second time. The Sawtooths (and White Clouds) were absolutely spectacular and easily cemented themselves into our array of favorite places. We will definitely be heading back there, especially since they are within striking distance of Mount Shasta.
On the way there, split the trip up and spent the night in eastern Oregon's Strawberry Mountains, which were also very, very cool and we committed ourselves to returning there in the fall, when the larch are gold.
Although the trip was quick, it was quite satisfying for both of us.