I have visited Bolivia many times in the past 12 years. Naira Hostal is the perfect stop-over in La Paz. They are located in a very public area, on easy public transportation from the airport. The desk will arrange safe taxi trips, change your money, store your bags if you use it as a base for traveling, and give advice about travel agents and trips. They have a 24 hour guard, a great free wi-fi restaurant, with a big breakfast included.