I'll try to offer a few thoughts, but since I'm not a regular Lightroom user (and haven't used it for some time) there may be others who can add to this. I do use Adobe Bridge along with Capture NX2 and Photoshop CS4 and View NX.
View NX has some basic tools for saving, retrieving, sorting, searching, rating, viewing, etc., but it is not as powerful as Bridge and certainly not as powerful as LR. The big advantage of View NX compared to the Adobe products is that you can see whether a NEF file has been edited in Capture NX2 and the file preview will display the file as edited. So, if you are using CaptureNX2 as your primary or exclusive editor, ViewNX might make a lot of sense but you would lose the additional features of LR. Notably, View NX lacks keyword capability and it is simply a file browser rather than a database. View NX might work fine for you if you don't have a very extensive or complex set of files and don't need to manage offline files. It is free so you could certainly try it. For what it is, it works fine.
In Bridge, I can easily open a NEF file directly into Capture NX2 by right-clicking on the thumbnail and selecting Open With Capture NX2. I would be surprised if something similar isn't possible in LR. In Bridge you can modify the file associations under Preferences.
Bridge will show whether a NEF file has been edited in Adobe Camera Raw and I assume that LR will show whether a NEF file has been edited within Lightroom. But you can't see NX2 edits.
My own workflow is to use either Capture NX2 or ACR as the raw converter depending on what I am trying to accomplish. However, I almost always end up further editing the file in Photoshop and save a psd file. For that reason I use Bridge as my file management tool. Of course, then you have to find a way to keep track of which files have been converted with which raw converter. Usually, this is simple because Bridge shows the ones that have been processed in ACR, but you could add a keyword or other identifying device.