LMB and drag a window from right to left selects everything the window crosses,
LMB and drag a window from left to right selects only complete items,
Then in the feature tree the items will be highlighted, hold Ctrl, RMB, and select add to folder about 3/4 the way down, name your folder, then I hide everything in the folder.
I can sort through a 500 item assembly in around 15 minutes.
As long as this is an assembly it works well.
That got it! The only thing I was missing was the Ctrl RMB when selecting in the tree. RMB alone would only select the single component, clearing all the other selections.