united stopped flying to santiago a few years ago. they will fly you outta denver then put you on a taca/lacsa flight. DO NOT DO THIS! lacsa/taca does not accept kayaks! you will be fucked when you change airlines. this has happened to me.
DIA is probably the worst airport in the U.S. to fly outta with a kayak. they see you coming a mile a way and they know exactly what it is. the "jungle explorer/surf ski" wont work. if you think you can get your boat on, whatever airline, it is always a good idea to bring someone to the airport with you so if they say no or $400 you can send it back to your place and not miss your flight.
boats are comenly bought, sold and rented in chile. what is it you want and what are the dates? i know some folks who can help you there.