I keep looking at Bitwig as a secondary DAW. I'm %100 on Cubase now, but keep thinking I should get something different to mix things up a bit. I've looked at Studio One, but it is very similar to Cubase. I'm currently looking at FL Studio and Bitwig - both are substantially different than Cubase.
I only have a few of them - String, Woodswinds, Guitarscapes, and one other. I, uh, "use them" by wasting hours of my life by making interesting sounds.
I do this exact same thing. I have different tabs for Kontakt Instruments, VSTis, Effects, etc. I certainly helps keep me honest on what I buy (or don't need to buy). Its been a great help to me.