WITH A PURPORTED 300 DAYS of sunshine a year, snow-covered mountains, and the red-earth beauty only known to Colorado, it makes sense that I can barely turn around without landing in a music festival. Not all are in summer under star-lit skies — UllrGrass is held in the short dark days of January, and Hollerween, where I have worked the door for the last two decades, is, you guessed it, at the end of October. Every small mountain town has a seasonal festival, but the lineup, location and philanthropic goal makes Rhythms on the Rio a heartbeat of the festival ...