Weird books are my jam! I’ll add a few I haven’t seen mentioned yet:

• A Short, Sharp Shock by Kim Stanley Robinson
• Up the Walls of the World by James Tiptree, Jr.

I read Hothouse this year and also loved it. Some reviews I saw complained about the one-dimensional characters, and I see where they’re coming from, but the crazy imaginative stuff you mentioned made up for it in my opinion. Now I’m curious to check out more by Aldiss. Crazy/weird is my favorite genre!