New York is a big, powerful city, and lots of New Yorkers like going to big, powerful gyms. But over the last few years, many anti-big gyms have sprung up, often resulting from the personal vision of founders. In recent weeks, I tried three independent gyms with very different pitches — each one excellent in its own way and attentive to members.

CLAY (25 W. 14th St., just off Fifth Avenue, 212-206-9200, insideclay.com)

Walking into serene and gracious Clay from rough 14th Street is one of those only-in-New-York experiences. Where else would an entrepreneur decide that the best location for the city’s swankiest gym (according to New York magazine) is a gritty, commercial street? Exactly that kind of self-confidence imbues Clay, which integrates physical training, mindful exercise, and nutritional guidance. The 20,000-square-foot space is full of natural light, from both the skylights cut into the roof and the windows fronting 14th Street, which has a charming Edward Hopper look from above.

Working with instructor Leslie McNabb, I started with a pilates workout on the reformer. Ms. McNabb made the kinds of precise adjustments that remind you of just how helpful pilates supervision can be. By turning out my left foot a bit more to match the right, for example, she showed me that I’d been giving in to the weakness of the left leg. Next I met with nutritionist Christy Maskeroni, who says she helps give clients the tools to make the right decisions about lifestyle changes. She administered a basal metabolic rate test, which told me I can consume roughly 1,630 calories a day with no exercise — and a whole lot more with exercise if I want to maintain my current weight. She works closely with the chefs in Clay’s organic café to ensure that nutritious, low-calorie meals are on offer.

When I asked for any highly nutritious but low-fat smoothie, I was handed a vanilla-nut shake that was so delicious I started to worry about whether it was really as healthy as it was said to be. I was assured it was.

Then came the pièce de résistance: a session with trainer Kenny Mahadeo, a wiry, cheerful man who believes in mixing up the exercises to keep clients engaged. We began with abdominal exercises, done as I was draped across an inflated balance ball, and then warmed up further on the treadmill, alternating easy jogging with sprints. Since I had mentioned I used to Rollerblade in Central Park, he had me work out on the “slide,” a slick surface on which one pushes off from side to side like a speed skater. We alternated the slide with deep lunges and did push-ups hanging off the ball on which I’d started. He then tethered me to a rubber resistance pulley that he held like reins and had me run forward and backward. I suddenly knew how my childhood pony felt.

Cost: Initiation is $525, which includes five customized sessions to be chosen from private training, pilates, and spa treatments. Annual membership is $1,950. Membership is capped at 2,000 people.

SMART WORKOUT (124 E. 40th St., between Park and Lexington avenues, 212-661-1660, Suite 603, smartworkout.net)

Smart Workout — a friendly gym that wants guests to feel like they’ve been invited to a friend’s home for an exercise party — was the brainchild of two friends, Lois Cooper and Elaine Platt.

Inside, the space looks like a small apartment in which the hosts have moved the furniture out for the evening. Better yet, the 15-month-old Smart Workout has a unique hook: It offers unlimited semiprivate training for one all-inclusive membership fee. You name it, they have it or will at least try it to see if members respond. Yoga, pilates, pole dancing, tango, trampoline classes, cheerleading, and boxing are among the options.

I took two 45-minute lunchtime classes. The first was Zumba, taught by Courtney Zbinden, a beautiful dancer, who moved everyone through the Latin steps so gracefully that we didn’t notice how much we were sweating. Next was “On the Ball,” which was great fun — bouncing up and down on a ball, twisting the prop, reaching over it, and stretching across it to 1960s music.

Sessions on the pilates reformer alone make membership a bargain, since most other gyms charge extra for the reformer. I did an evening session with instructor Megan Frummer, who adroitly managed three skill levels even as a ballet class was going on directly behind us. The whole experience was blissful: We lay on our backs, doing pilates frog movements while the lights of Murray Hill glittered through the windows and “Swan Lake” played over the sound system. I half expected Mikhail Baryshnikov to jeté in momentarily.

Cost: Initiation is $200, and the monthly fee is $135. Another option is to pay $1,485 up front for a 14-month membership (no initiation fee). Smart Workout caps its members at 150 people, so there’s no wait for the equipment.

THE GYM (11 E. 26th St., between Park and Madison avenues, 4th Floor, 212-889-3003, thegym.com)

In opening the first Equinox in 1991 on the West Side of Manhattan, the Errico siblings — Danny, Vito, and Lavinia — revolutionized the health club business in New York. With its sleek facilities, top-of-the-line equipment, excellent classes, and obsession with cleanliness, Equinox quickly became a major force on the fitness scene. In 2000, the Erricos sold the chain, reportedly for more than $100 million — and turned their attention to creating a boutique gym on Madison Square Park.

The point, according to the Erricos, is to return to the basics of the neighborhood gym but with state-of-the-art equipment and unique classes. In collaboration with a group of professional athletes-turned-trainers, the Gym has recently introduced two workout techniques. There’s the FreFloDo, which works off a so-called Launchpad, a special treadmill without console or handrails. Trainer Ike Smith, a former professional boxer, started the session by showing me how to get on and off the Launchpad — clearly crucial since the track keeps moving. Once I had that down, I ran in place, backwards and forwards, tried sidesteps, and leapt on and off at his command. Mr. Smith then picked up two light bats, which he twirled slowly, telling me to run at him, touch him, and back up — all the while evading the bats or taking a penalty of having to start over. Anyone who wants to improve endurance, agility, or fast feet — boxers, soccer players, tennis players, and dancers — will find FreFloDo riveting and invaluable.

That same afternoon, trainer Carolyn Pautz led me through a half-hour session on a vibration machine called the Pineapple, which I had once used in London but never thought I would see in New York. The ancient Greeks apparently noticed the efficiency of having athletes work out on vibrating platforms — the effects of a 60-minute workout can be achieved in 30 minutes, so it is said — but the precise science is not yet understood. Ms. Pautz had me do butterfly and breaststrokes using the orbital levers, followed by a series of squats and lunges. I tired in far less time than usual but felt exuberant afterward.

Cost: No initiation fee, and $125 monthly.