Maiki had her 1st My Gym class last Thursday, and it was AWESOME! I think it's well worth $55 for a four week session. Here's a link to the site if you want to check it out.
http://www.my-gym.com/layton
They rearrange the gym every week, so the kids don't get bored. They also have once a week freeplay, and once a month parents night out.