Circle gym and spa is nice though I'm not sure about PAYG options. Fit4less is more welcoming than might be assumed, it isn't that busy compared to PureGym and other low cost gyms and I haven't noticed "attitude" and not entirely young. Columbo centre is more mixed in terms of age but haven't been there.
I use the Castle regularly and can recommend it. I work the weights and machines and they're always in good order. They had an airconditioning problem a few weeks back which helped loss a bit of extra weight(!) but it's all good now. I'm 59.
Staff to my mind are universally excellent. Always on hand to offer advice and yeah, no attitude. Old and young guys pumping weights and much fitter women of all ages mixing it up with good cardio work and of course there are many other activities within the centre to keep you from getting bored from a regular routine.
Never made the Castle today but that's high praise Tolstoy. I will definitely try it.
Few others at Cotton's are handing their notice in. If I didn't know better I would say it's being run down, which doesn't really make sense as it's their flagship branch, apparently.