Bookable through
Google Flights or on
PricelineFlights as low as $509 from Seattle and from $550 from Chicago (not all that terrific)
SEA-CUN Example Dates:8/15-8/22
8/15-8/23
8/16-8/22
8-16-8/23
8/23-8/29
8/23-8/30
9/6-9/12
9/6-9/13
9/11-9/17
9/11-9/18
You get the idea...Tuesdays and Wednesdays through November.
ORD-CUN -
Tuesdays, Wednesdays, and Thursdays through May-March.HT:SF