2 week itinerary South America
 

I only have 2 weeks to spend in south america and was wondering if the following itinerary was possible, what the best way to get between places is, and how long I should spend in each place.

Buenos Aires - Iguazu falls (both sides) - Machu Picchu / Sacred Valley - Lake Titicaca - Back to Buenos Aires for flight home

Any advice would be much appreciated! Thanks

Possible? Yes but it would be very, very rushed. You would need to fly between places and direct flight may not be possible. you would almost certainly need to return to BA to get to Cusco, probably via Lima. That would be both expensive and time consuming.

Nights:
BA - 1
Iguazu 3
BA - 1
Lima - 1
Cusco and the sacred Valley 4
Titicaca 2
Lima - 1
BA -1

One night in a place really only gives you a few hours to explore. 2 night will still only give one full days.

Not sure what nationality you are but you may need to factor in immigration fees which in some case can exceed $150.

IMO in two weeks i would stick to Peru. there is a huge amount to see and it is much more enjoyable at a slower pace

Depending on where you live, flights are generally overnight between your home and South America. Looking at your itinerary I would do the following:
Day 1: FLY
Day 2: Arrive Buenos Aires
Day 3: Buenos Aires
Day 4: Buenos Aires
Day 5: Fly to Iguazu (Argie side)
Day 6: Iguazu (Brazil side)
Day 7: Fly to Lima (can be done direct from Brazil side of Iguazu- check visas)
- possible overnight at airport hotel depending on when you arrive
Day 8: Fly to Cuzco
Day 9: Sacred Valley
Day 10: Machu Picchu
Day 11: Cuzco
Day 12: Train to Puno (only on certain days)
Day 13: Puno
Day 14: Flight to Lima and back home
Day 15: Arrive

As somone else suggested, this is pretty rushed. Culinary tour / Barranco is fun to see in Lima which you wouldn't have time for.