There are some fare deals out of San Diego with American and Delta competing on a few routes to Central America and Caribbean with ticket prices from $290 to $355 for places like San Jose SJO, Costa Rica; Montego Bay MBJ, Jamaica and Havana HAV, Cuba.
Jamaica routings tend to force an overnight. Havana requires a visa. Costa Rica in winter is peak season weather and looks to be the most suitable route to expand upon due to reasonable flight schedules.
San Jose SJO Costa Rica can be priced as one way fares using either AA or DL.
Delta Airlines San Diego SAN – LAX – San Jose SJO, Costa Rica
The advent of Basic Economy fares means you might need to add $17 each way for the privilege of seat assignment at booking and a checked bag.
Delta Airlines San Jose SJO – LAX – San Diego SAN