The ProRes of Premiere Pro?
There's a philosophical difference between delivery codecs (e.g. mpeg4, avchd), editing codecs (e.g. DNxHD, ProRes, Cineform), and capture codecs (e.g. r3d, DVCPROHD).  While almost any codec can be used for each of these three stages, your workflow needs will help you decide which are best suited for each stage.

The question you seem to be asking, is "Which editing codec should I transcode to for an online edit?".  Editing codecs are generally less compressed and larger on disk, to make playback simpler from a processing perspective.  It's definitely possible to use ProRes in Premiere, and coming from DSLR (as of July 2011) 422 is probably (technically) overkill, but it is a reasonable default choice.  Another editing codec option to consider is Cineform, since you can get the 1920x1080 codec for free now, as part of the GoPro Cineform Studio package.

There are even specialized tools to help you with transcoding batches of files, such as Magic Bullet Grinder.  If you're concerned about editing speed, there's even a chance that Premiere and your computer will be powerful enough to slog through your capture files as-is without transcoding, saving you from this step altogether.

As always, try it for yourself, and test, test, test, your workflow before putting it into production.