A large number of the chain gyms i've seen recently are actually good, unbelievable assortment of top equipment-weights, cardio that outdoes what alot of the old-time gyms had..what alot of them lack isn't facilities, it's the right vibe. Since it's mainly mainstream people that sustain them, the ambience or lack thereof is something like being in a libary. Not always, but alot of the time, unless you look around for the exceptions.
But in terms of the equipment itself, it's mainly been big-time improvements, being able to find serious equipment all over the place vs. being in NYC in the mid-70s and having to try to unearth just a few holes in the wall with weights. It's remarkable how far things have gone that a decent amount of the population does lift and do cardio, even though as you'd expect from the mainsteam, it's usually done with minimal intensity ie the guy i see on the treadmill on the cell, reading a mag, or the guy curling a DB while on a call.