I read several of my, now ex-, brother-in-law's scifi books back in the early nineties without really paying too much attention to the titles or authors; just wanted something to read. One keeps coming back up in memories every now and then and I would like to read it again. It wasn't a short story but it may have only been novella in length. 

The story was about a human from Earth who went to Jupiter (maybe Venus?) and communicated his adventures there back to the book's author on Earth via telepathy (mentioned in the opening chapters). On his initial decent down to Jupiter, he encounters, just below the cloud canopy, incredibly tall trees in which people live. If I recall correctly, there were some rather large spiders up there, too. He eventually makes it down to the ground and travels all over the planet on his adventure. I'm having difficulty recalling any further scenes from the book other than bits and pieces that are hard to describe, let alone put in context. And that's even if they're from the same book.