What you are looking at is to skip the last segment. Do not check luggage, as you won't be able to get it in SFO. Do not tell the airlines your intention, as they can invalidate the ticket or charge you for the GIG-SFO trip at the $1000+ cost. Also and most important, if you plan on doing this, make sure that you are skipping the last segment of your ticket, as the airline can and will cancel all other portions. So, if doing a-b-c-b-a, and you skip c, the b-a portion is automatically canceled due to no show on c. Get it?