When I arrived at CERN back in 2003, there was a pile of Sun workstations on a corner from my office, waiting to be dispatched to computer heaven.
Most folks were either using the new OS X, or Windows, with a custom Linux distribution on the servers, eventually replaced by Scientic Linux distribution.
There were still some Sun stations kind of serving the X Windows sessions on the restaurant area, and even those didn´t last much longer.
Late 90s / early 2000s was when Sun workstations changed from very expensive but well constructed proprietary machines to very expensive PCs with cheap internals and unusual processors. However I still got an ex-university Sun workstation around 2002 for free (or a token price?) which served me well as a desktop machine for years and years. It eventually died of the capacitor plague that (to be fair to Sun) affects just about everything from that era.