I love GWL too. I get regular emails from them. I have only stayed there once but we are planning to make it a yearly getaway. Can you please tell me where you watch for codes? Thanks.
The Great Wolf Lodge website is the best resource. They are regularly offering packages or incentives for different time periods. I, too, am on the mailing list, but not all of their offers are emailed out. So check that website often!!

Normally, they only offer a certain number of their rooms under any promotion, so if its a popular time period that your're travelling in (or a really great sale), you won't want to delay in booking those rooms.
Also, another "secret" to a great rate is to reserve early. This has paid off HUGE for us on more than one occasion. Great Wolf's rates are based on occupancy levels. As occupancy increases, so do their rates. So generally speaking, booking early will get you a much better rate (and they will apply other discounts to your stay as they are released.....just call the reservations line and they will adjust your rate accordingly). Here's a great example:
This year, we're staying from June 28th to July 3 (5 nights/6 days). We booked in early March for a room-only rate.
In May, they released packages for our time period. So I booked the first night under their Grub N Putt package (buffet breakfast for 4, golf for 4, and 40 arcade tokens), and the following 4 nights under their Two Inclusive Package (buffet breakfast each day, Pizza Hut lunch each day, buffet supper each day, plus Cub Club craft, arcade tokens, and mini golf for each of the kids). Add in the taxes, and it was just under $1650 for the five nights. With all the food and extras added on, our rate became LESS than the room-only reservation (which was just under $2000, taxes in).
If you were to reserve a room-only right now for that same time period, you're looking at just under $2500 WITHOUT the taxes.

And that's no food, no golf, no arcade tokens......just the room and waterpark passes.
So it pays to book ahead!!
They recently released a pre-summer sale where you got $100 a room-only rate if you booked by May something-or-other. When the offer was first released, there were rooms going on Sunday nights in July for $119! The next day, they were up to $139. The following, $169. Now......well over $200 (and most of that promo is now sold out).
We are huge fans of the Lodge....if we can't get to Disney, Great Wolf is our next choice.