Well, these are my honest opinions and i am sure that I'll be corrected if wrong. Keep in mind I do not fly an airline, just my observation and results from research.
One of the best way to learn something is to be able to teach it. The CFI/CFII/MEI would definitely give you experience and knowledge that would not be wasted.
The sim would obviously give you the experience to fly an RJ but if your company would pay you to do it, it would be rather pointless to pay for it just to fly that "shiny jet."
There are definitely more avenues to gaining the experience and knowledge of flying. Where teaching or military are the more popular ones, some folks(like myself) would just prefer not to teach whether or not they fly for an airline now or a little later. In other words, if teaching is your thing and you have the opportunity, go for it, forget that pretty certificate that says you can fly an RJ. If teaching is not really your thing, think outside the box. Whatever you do, get more than just a piece of paper you spent 1 week out of your life for that says you can fly a jet that flies itself.

Disclaimer: Please keep in mind these are my opinions and not meant to put down anyone who has chosen military or instructing as their path.