I have a trip from SEA to DEN and looked at this promo, it’s $39 per ticket and as a family with 2 adults and 3 children we would essesntially get 2 free. After joining the Den, paying for copious amounts of ski bags and payment for a seat, it would be $350-400 for all 5 of us. Would be $450 or so with DL or AS, but we get free bags/seat assignments with them and they have more flights w better timing. Not sure saving at most $100 over 5 pax makes it a good deal.