Targeted Group Networking @ BB's

Is it OK to target a group at a BB you want to work for, rather than the larger BB itself, and network with a lot of people in that group (i.e., asking for "career advice" or whatever?

If so, what is the most effective way to go about doing this? Targeting Analysts/Associates, or only MD's, or maybe asking a couple of Analysts out to coffee, then a VP, and maybe an MD? In what order?