We drove over a portion of Mt. Shasta which erupted in 1786.
So we decided to visit Mt. St. Helens, which incidentally erupted 35 years ago in 1980, I remember because I was 16 and I could see the eruption from my home that morning. The Mountain has since erupted once again in 2008.
One fun vacation memory: The most requested song on Grandma's Ipod?