I�d use Spirit airlines which is a spinoff of Korean if you�re price conscious, transit over Los Angeles and then connect to a Delta Code share flight. Alternatively, Delta have published through fares.
I looked at other options, such as flying to Havana then using an onward fare and I compared net fares between Seoul and Los Angeles, and fares between Los Angeles and Guatemala City, but the fares work out higher.
Have a look at
http://www.kayak.com for numerous comparisons, which will save you multiple searches through other on-line carriers. Additionally, you �might� consider one of the Oneworld Alliance Trans-pac fares at: www.oneworld.com
I recently flew London-Santiago-Auckland-Sydney-Hong Kong-Los Angeles-London and the fare came out to approximately USD$1950.00, so from a currency perspective, you may be able to get a similar value.
Best of luck
Fr Bill
http://www.projectnewlife.org
http://bigworldsmallboat.blogspot.com