absolutely love the climate, as well as it being a "non tourist" city. I felt very safe there and would move there in a heartbeat. Check out the Cristo, go to the Mercado, but don't get lost. The food is fantastic and inexpensive. Santa Cruz is more tropical. La Paz is difficult with the altitude. Love Bolivia
If you want to give to the people living on the street, don't give them money. You can give them your leftover food or buy some for them. I absolutely love the country and the people. Pickpockets are around.
Generally felt safe. Stick in groups if you can. The food is fantastic. Watch for areas around the Coca Triangle. The people are lovely, beer is good. Pickpockets are common, and they are good.