Peru:
Lima
Stay at Loki Hostel. Other than that I didnt really do much.

Huacachina
Huacachina is a lagoon city in the desert near Ica, but Ica is boring so stay in Huacachina. Go sandboarding for $13 american and ride in a dune buggy...stay at Casa De Arena Uno or Casa De Arena Dos where they have a cool bar/restaurant and amazing desserts. Also try the hooka. The Lomo Saltado at the hostel is awesome and both have pools for swimming.

Arequipa
Go on the 3-day Colca Canyon tour to see Llamas, Alpacas, the worlds deepest canyon and take pictures of the largest condors in the world. Arequipa is pretty tame other than that.

Cusco & Macchu Picchu
Stay at Loki Hostel (almost 170 backpackers at a time) and party like youve never partied before. Lots and lots of wild all night parties, eat 1/4 chicken with fries and salad during the day and stop by the market for fresh juice from the ladies for $.50. Catch the train to Aquas Caliente and stay at the Eco-Hostel called ______ (something) Wasi. I cant remember the name of the hostel but it was cool. The next day the bus leaves for Macchu Picchu at 5:30AM...be there early or you wont make the 1st bus and you will miss the sunrise. Bring lunch and lots of money b/c Macchu Picchu is EXPENSIVE. Lunch there is like $20 American so bring a sack lunch. Also, hike up Hyanu Picchu early like 10AM because after that the lines get really long.

Puno
Go on a boat tour to the reed islands and Tequila Island.

Bolivia
La Paz
Stay at Adventure Brew hostel, book a trip with Gravity to mountain bike down the worlds most dangerous road. Bring like 10 layers for the morning and shorts for the afternoon. Temp changes from 35 degrees to 85 degrees while biking. Also go to the black market (Mercado Negro).

Cochabamba
Worlds largest market. Freakin sweet.

Potosi
Tour the mines. Very tight spaces but amazing experience.

Uyuni
Tour the Salt Flats on a 4 day tour in a Toyota Land Cruiser 4x4. Get them to drop you off in Chile after the trip instead of riding all the way back to Bolivia.

Chile

San Pedro de Atacama
Stay at Hostel Florida. Eat at the restaurant across the street from the hostel with a picture of lightning and a little girl in a door that has 666 written on it. I dont remember the name of that restaurant though, but best food so far on the trip. In the restaurant, there is a great selection of wine.

Santiago
Just went out. Stayed at Casa Roja and had an amazing time partying there.

Argentina

Mendoza
Bit boring for me, dont stay in hostel Itaka. Stay in Hostel Damajuana, and if its booked go to Campo Base 1 or 2. Lot of good wine though and wine tours.

Cordoba
Stay at hostel El Refugio and go skydiving. Its amazing and fairly cheap. Eat at Betos for amazing steak.

Buenos Aires
Stay at Hostel Milhouse (100 backpackers) and eat the best steak of your life at Desnivel. Go to a Boca Jrs soccer game or River Plata soccer game. Visit the cemetary and take pictures of the above-ground graves. Walk around the city and on thurs catch the mothers of the disappeared at 3:15PM in Plaza San Martin.