Any of the Mexican beach towns should be fine: Acapulco, Puerto Vallarta, Cancun ...

If you can swing it I will repeat advice I offered in another thread: Costa Rica. Probably a little more expensive to fly to, but less touristy.

I would get one person in charge of checking a few web sites to see if a sale pops up (you can also set up email alerts) from both SEA and BOS, and if that happens get ready to pull the trigger quick. Of course if the BOS folks have never been to Hawaii, and they don't mind the long trip, you CAN get there from New England

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