Yuri's Revenge never gets old - it's just the right balance of RTS with a bit more of an arcadey feel. Sadly I missed the original Starcraft train (finished Starcraft II), but one of these days I'm going to sit down and work my way through it.
By pure coincidence, both Starcraft 2's writers and /me believed that Kerrigan should be brought back to her human form in Starcraft 2 :)