I have been a member of Planet Fitness for about 5 months now, and I really do enjoy it!
Their stretching zone is perfect for my floor exercises, and I can usually get in my cardio on one of the many ellipticals or treadmills.
The only down side of the gym is they do not offer one on one training, which I really need and enjoy.
The closest thing they have to personal training is there PE class, which I have not taken, it is meant for small groups and I prefer to have someone focusing on only me!