Reading this thread gets me angry with myself for playing the game instead of reading. So many books, so little time
Gotta mention James Hogan's Giants series and agree with the recomendation of Mote and the sequel Gripping hand by Niven and Pournelle, a first contact masterpiece. I love Niven's work but I am over the Ringworld series (there have been at least 6 of them) and I hope he is as well. The first couple of them were great but it turned into a Rishatra festival.
Anything by Vinge is a must read. The Peace War and Stranded in Real Time are incredible.
OBTW those of you that liked the Hyperion series, read Illium and Olympus, you won't be disappointed.
Naturally you can't be content until you have read everything that Asimov, Bradbury, Heinlien, Simak and P. K. Dick have written.