David, your health and recovery is the priority now, so don't worry that you have disappointed anyone. It's much more important that you physically recover, and everyone on the Adventure "trail" understands that, I am sure.

Sorry you'll miss seeing the elk, bison and geysers in Yellowstone! Steamboat geyser, the largest in the world, recently erupted after many years of no eruptions. It happened early in the morning on May 2, and the witnesses were people who had illegaly parked in the parking lot overnight to sleep. They thought it was an earthquake, then stepped out and saw the huge plume of the geyser shooting above the treetops of the forest.
Steamboat Geyser eruption w/ photo -click here

Alice