There are several airlines with Los Angeles to Boston at $80 one way for dates in February. American, JetBlue, United and Virgin America all have some dates in February with $78 to $80 fares.
Finding a round trip fare for $160 over President’s Week holidays is possible, but you may want to fly two different airlines to get the lowest price or best schedule.
United Airlines Los Angeles – Boston (return via SFO)
$160.20 round trip Saturday February 13 – Sunday February 20, 2016
American Airlines Los Angeles – Boston (nonstop)
$186.20 round trip Friday February 12 – Wednesday February 17, 2016