We spent a couple of nights last June in the Traverse City location.
We live in Michigan, but it was our first time in TC. We're not really into sand dunes or beaches, so we spent most of the time at GWL. (We did visit the Music House Museum, though, which is great if you're into nostalgic instruments and the like.

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The resort itself is cool for kids. (This isn't really geared at all toward grown-ups, save the spa downstairs.) You can load a lot of money into MagiQuest, but we only bought a wand for our daughter (6 yrs. old at the time). There are a lot of upgrades you can buy (wand attachments, costumes, etc.) The MagiQuest staff stays in character.
We spent a huge (HUGE) amount of time bouncing up and down 3 flights (elevator and stairs) amidst many, many kids and their parents. Hubby and I were exhausted, but DD loved, loved, loved it. You buy the wand once, and you can use it again at other GWL's at later dates. They also had a tv channel in the rooms with the backstory and more info on MagiQuest.
GWL has programs for kids (the name eludes me right now) where they can craft and do other things with GWL mascots. They also have a bedtime story animatronic/live action program in the lobby in the evening. We had cookies brought to the room before bedtime for our daughter by GWL mascot Wylie, I believe.
The downstairs arcade is fun. Reminds me of a cross between Chuck E Cheese and Dave & Busters. Decent prizes.
The restaurants are pricey, and the food is just okay. We would have preferred to go to the family restaurant up the road. Better food and cheaper. (You can also use the MagiQuest wands in the restaurants onsite.)
DD loved the waterpark. It was her first time to a decent sized waterpark. She didn't do the tube slides, but they have smaller slides, fountains and a huge fort. Her absolute favorite was the 'big bucket' countdown and then the massive waterfall on our heads when it tipped over.
I don't know if it was worth it pricewise ~ I think GWL could do better in that arena. But my daughter had a blast, we have memories, and that's what is ultimately the most important.
And besides, who wouldn't want to see grazing buffalo when you look out your balcony window in the morning?

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