Don't do what I did: I read Rendezvous with Rama then I read the last book in the series which completely ruined my chances of reading the ones in the middle.I just finished Rendezvous with Rama (very good, although the anti-climax at the end means that I won't be able to rest until I've read the rest of the series), and I'm about to start Destination: Void.
The Case for Mars is a good book, although it gets rather less grounded in reality near the end. Still, I hope we get to try it someday.