Northwest Mainline doesn't fly any RJ's. However, most of the time when asked where I work by the uninitiated (non aviation people), I simply say Northwest. As someone else said, you use the word "Airlink", "Mesaba", or "Pinnacle", and people give you a really quizzical look, similar to "Who the h*ll is that?" and you end up in a 20 minute discussion of the differences, similar to telling someone you work for Chatauqua or ExpressJet.
As far as Pinnacle -vs- Mesaba brand recognition is concerned, people recognize Mesaba much more easily if they travel Northwest much, simply because Pinnacle is a new name, in the last 5-7 years PCL wasn't very big and got booted out of MSP and DTW for a few years, and more important as of late, Pinnacle doesn't say "Operated by Pinnacle Airlines" like Mesaba does every time they fly.
Our F/A's started doing it once a few years ago and Pinnacle management specifically put the nix on it via an internal memo, saying that Northwest Management specifically wanted it to seem like "Seamless Service", i.e. confuse the customer into thinking there is no difference between the mainline aircaft and RJ's.
Personally, I don't give a rat's either way, as long as the paycheck keeps coming (however small it may be)... and don't get me started on pay rates and our current negotiations that start next week.