Several people have suggested staying in Urubamba before going to Machu Picchu. Do you have to go to Cusco first? So why stay in Urubamba?
Is flying the only way to get from Limba to Cusco?
I think it's going to be way over our budget to do Machu Picchu before going on to Argentina to see our son, who just moved there. It seems like it will cost well over $1,000 - $1,500 per person to do that part of our trip once we arrive in Lima (from the U.S.)