We went to the Altiplano. It was possibly the best experience I have ever had, I would recommend it to anyone who has the chance. The wildlife is amazing - vicunas and llamas are everywhere, and the scenery is unique. The locals are very friendly and helpful. The toilets in Socorama are the icing on the cake! ;)
From Arica, I took a bus to Putre, which lies close to the Parque Nacional Lauca. It was an amazing service, I got lunch and all :). Putre is a nice place to relax, but other then that there is not much to do around here. The next day I hiked a few hours around Putre. After realizing the scenery was much like that in Southern Bolivia, I decided to head out of the Park and back to Bolivia. However, that doesn't mean the park is not worth it! I had just spent a week in a similar environment so I opted to skip that to see other attractions in Bolivia.