My niece and I are almost the same age (10 months apart, and our daughters are also 10 months apart), and when we were little, we played with the Kenner Tree Tops Tree House a lot.
It had a rounded tree-shaped two-level house that you pulled open at the top, little people (not Weebles, though I always associate it with Weebles -- they had their own tree house) and best of all, a tiny bush that was the dog house!
It is apparently being made in a new version in Europe, Australia and New Zealand, as one of the videos below attests. It's called the Magic Klorofil tree house -- no, really! Sadly, they won't ship overseas. (Someone is trying to sell one on eBay for $300 last I checked--no thanks!)
Thankfully, my sister kept hers, and now my niece and I can bring our kids over to play with the same exact toy we played with as kids. Did you have one?