As far as I know, the gym is never locked up. I've been there as early as 5:30 am, and while I've had to turn on the lights, I've never been unable to gain access. There is a trainer in the gym; you could always touch base with him upon arrival to ensure that you won't have a problem.
I know everything, and I'm always right (just ask my husband).
We were there Aug 22-29, the gym is fantastic,open 24x7.
Lots of free weights, 4 treadmills, two ellipticals, a recumbent and regular bike and numerous upper and lower body weight machines, they offer personal training (yep its included) and classes yoga, step, abs etc. My wife did a step class the visiting trainer was from Arizona and she did a great class,they are outdoors on a shaded deck so bring a water bottle. She will run the class even just for one which she did fwith my wife.
If you get there at 5:00 am to 6:00 you will workout with Brian the water sports manager, he will share many stories with you.