Haha! I found a random W95 install disk only the other day and instantly thought "wow, I remember that!" I was in charge of evaluating W95 for the company I worked at at the time. Obviously we went with W95 as it was great but it was a great shame as I'd implemented OS3/Warp on the production machines and it was so much better for what we were doing (I could squeeze so much more memory out of a DOS box, which was critical for our heavy duty data processing app)
My last new OS installation (Amiga OS doesn't count) that required floppies was Linux. 37 of them if I recall correctly. I think that it was Redhat 5.1 (about that time Redhat also had "Redneck" as one of their installation languages).