I finally got to the Greenies sim last night. Fun place! Full of interesting corners to explore and interactive objects. The flow of the place is great; you start in a tunnel, go thru a (scaled to avatars) dollhouse, then enter the giant-scale main space. The movement between the lower and upper parts of the sim was easy and fast. Here's some pics.
I'm fascinated by spontaneous games - the ones people make up for themselves outside of what seems planned. Almost everyone roaming around in the house part of the sim was racing around in vehicles sooner or later. I wonder if it is intentionally seeded; there's a free UFO available in the upper part of the sim, and one of the greenie displays has the aliens playing with a remote control vehicle. Was that display there before visitors started racing around?