My previous workflow was air-tight and very efficient:
Edit in Final Cut Pro 7, send to Apple Color, run color corrections in the "primary in room" and then grade in the "primary out room" with slight variations depending on project. Render everything out, send back to FCP to run through audio mix and export.
However, now in Premiere Pro CS6, I've been searching for the most efficient and effective route to pursue. Tried Speedgrade and HATED it. Have been able to run some very annoying round-trips through Apple Color from Premiere via DPX sequences, but the speeds have not been lining up. I'm currently looking into DaVinci Resolve 9 (Lite) as a switch from Color. The workflow would then be:
Edit in Premiere Pro, export XML, open directory and XML in DaVinci Resolve to run through color corrections and then grades, then export from there or send back to Premiere via XML depending on the project and how Resolve actually works (haven't actually done this yet).