Another Lem story which is more along the lines of a traditional alien encounter is FIASCO. In this an earth ship travels an interstellar distance to the planet they call Quinta, where they encounter bizarre and apparently hostile phenomena presumably attributal to life forms there, but which they cannot contact or identify.
When I read this some years ago I cheated and peeked at the last page, where I saw that the last line was, “... he realized he had seen the Quintans.” This charged me up a bit so I finished the book.
SOLARIS is generally a better story, though. A classic in fact.