The $500 gift card promo was only offered to certain people, and it worked like this

$100 southwest gift card with $1000 in purchases
another $150 with $1500 more
and another $250 with $2500 more

Total of $5000 required. I applied under this promo (no fee, 16 credits and the $500). I have already gotten the first two, and have spent enough for the first two gift card levels. So we'll see if it works out.

Southwest targeting is getting pretty insane; I collect the offers for my wife's account, and hence I got two emails -- one for me offering quadruple Thrifty credit, and one for her getting double Thrifty credit. I can only imagine what a typical office of frequent fliers must be getting.

You guys can try and see if it works for you, because the promo code are different
WN23 for double Thrifty credits
WN4 for quadruple