Mariner Square Athletic Club

I had a membership for a few years at Mariner Square Athletic Club in Alameda (just through the tube), and always loved how anonymous it felt in that regard. Lots of different people, shapes, and sizes. Their classes are great (yoga and zumba, specifically), and they have a pool. Also, if you ever want to walk or work out casually sometime, please feel free to hit me up. I'm also middle aged and woefully out of shape.
:)

Hi, I go to the Mariner Square Athletic Center in Alameda, and it meets your criteria and not much further than the Oakland Y. It's just through the tube from downtown Oakland, so practically in Oakland. There is a big parking lot, and it is next to a large shopping complex with even more parking. There are a wide variety of folks going -- plenty of seniors and middle-aged folks, plus younger folks, lots of different body types including overweight. There are a lot of amenities (pool, hot tub, towel service, etc.) and a lot of great classes, some of which are taught by seniors (it's not a place where all the instructors are 25 and buff). There's also a large variety of classes, with some more intense and some more gentle. I particularly like Cardio Sculpt or Step Combo with Thomas; it's a great combination of aerobics, step routine, hand weight lifting, and core exercise, plus stretches, that is easily adjustable to all fitness levels and the teacher is great and makes everyone feel comfortable and have fun. If your kid/kids are young, there is an excellent onsite child care for babies through I think age 12, not sure on upper limit. I recommend it.