Ok assuming that your title SCL (Santiago, Chile) is a typo and you meant SLC. If you want to fly earlier or change flights, you can choose to Same Day Confirm which will give you different flight options for $50 (free if you are a GM/PM). SFO would be an option IF there were no other options and you'd most likely be on your own for transportation. Unless it is Delta's fault, it is unlikely they would rebook you on another airline. Just a question, what's the dear of flying the last flight of the day? Everyday, thousands of people fly last flights of the day without problems.
http://www.delta.com/traveling_check...es/index.jsp#1