I can't believe no one has mentioned Devin Harris but that people have mentioned Jameer Nelson. I think, at this point, Harris might be better than Rondo. He is a tremndous defender, a scorer that gets to the line a lot and can hit his FTs(82%). He also is a very good passer, if not in Rondo's league, and has a very good assist to turnover ratio. He doesn't have long range on his shot but he is pretty decent as a mid range jump shooter.
What has all this got to do with Rondo? Well, I think they are amazingly similar players in terms of overall quality and I think Harris' contract is the one Danny will point at as the benchmark for any future Rondo contract. Harris has 4 years and roughly $38 million left on his contract, numbers I think the C's will work towards and that Rondo should be happy with.
Now, Rondo's side can argue, and I believe correctly so, that Rondo's game is still growing and that he is 3 years younger than Harris and has proven himself on the biggest stage. I think he will also be able to argue, correctly so, that Harris' game may have plateaued whereas Rondo has superstar potential.
Either way, I think negotiations will involve a lot of comparisons between these two players and their respective contracts. Personally a 4 year/$39.3 million contract with years of $8.5M/$9.392M/$10.285M/$11.177M and a team option of a fifth year at $12 million is a really good contract for Rondo that both sides should be able to live with.