I climbed Illimani with Climbing South America, based in La Paz just last week and I can say this is a wonderful mountain to climb. Not technically very difficult but fairly exposed in certain areas. Even the drive from La Paz is an epic - some 3.5 hours to Pinaya, from there the usual 3 night 4 day ascent begins. The views back to La Paz at night are incredible and the higher one goes the icsta opens out west to the volcanoes on the Chilean border, Titicaca and Peru to the north west and from the final summit ridge (assuming the normal Pic Sur route) the views east over the Bolivian and Brazilian amazon isn't so bad either. If you feel the urge and have even a little experience, this is a must climb.