I've thought the Castro Valley looked like a good value for a commuter at the MSRP. At $600 its even better. The frame (same as Volope according to Bianchi) seems to be a good cyclocross/light touring frame.
It could be converted to a double but it would require a new chainring, two if you want them ramped, a front derailer and a front shifter. That will be a noticable expense but the single chainring should be suitable for 90%+ of your needs.
Craig