To clarify - there are 2 separate gyms. The 'cardio center' is free for guests. It has a wide variety of cardio - 12 treadmills, plus ellipticals and bikes. It DOES have a small free weight area - full set of Dumbbells, bars, mats and a couple of benches.
The spa gym is $30/day and is massive and has all the machines you could want. But if you're just trying to get in a good workout with basic weights and cardio, you can get everything you need for free in the cardio center. There's also a short little loop around the pools (maybe 1/4 mile?) if you want a few minutes of fresh air.