you have to agree that going with a tried-and-true RDBMS that's been around for decades is a much better prospect than choosing one of the new, unproven NoSQL products.
I disagree. Like I said, CP vs AP are two very different strategies for addressing mutable shared state, and there are no AP RDMBSs that I'm aware of. If your system dynamics are fundamentally AP, no number of Oracle Exadata racks will do the job. If your dynamics are fundamentally CP, Riak, SimpleDB, and Cassandra will make your life a living hell. Few applications are all-AP or all-CP, which is why most teams I know use a mixture of databases.