We go to a lot of different playgrounds; we're lucky to have so many to choose from. I've been noticing what's changed since I was in grade school where we had a recycled tire playground and a few metal structures and jungle gyms. Of course there's a lot more plastic now and that means static electricity when going down slides! The variety of the play structures is amazing, we really just had different orientations of metal rods if I distill it down (and ignore the tire playground creations which were too hot to play on when it was sunny anyway). The two freestanding items that astounded me recently were the Kompan Supernova, a freely (and easily) spinning ring that you can sit on, walk on, stand in the middle of, and the Infinity Climber (which is not a Mobius strip, but there is another product from a different company called the Mobius climber). Our son (he's 2) loves all slides and so his first goal at any new playground is to try them all out, no matter how high up they are. He will climb things that I would not have attempted when I was years older than he is.
Here's a video of the Kompan Supernova.