A while ago (like a long while ago) there was a post that no longer exists (that I can find) that listed a really good order to play the content in.
I remember Operation Anchorage was first, and I believe The Pitt was second. The rest is where I get fuzzy. I know it said to at least play up to the quest Picking up the Trail, but not completing
Spoiler
Now I can't remember where Broken Steel, Mothership Zeta, and Point Lookout fall. I think Mothership Zeta was going to be next, but I simply can't remember, and I totally can't remember when I was going to do Point Lookout and Broken Steel.not entering the vault you're searching for.
So yeah, I took a long break from the game and completely forgot all the stuff I was planning on doing. If anyone has some insight on what order to do things in relation to the DLC's I'd really appreciate it.