Oh yea, definitely replay games that I enjoy. Like you saw from one of my other posts Skyrim was on the top of my list, at least until the next Elder Scrolls game comes along. That may not seem like an "old" game, but just think, it came out nearly 4 years ago! That's pretty old in game years now-a-days.
I tend to focus on one game for about 70% of my gameplay (until I feel the need to move on) and then have 3-4 peripheral games going to break things up. Right now I've been investing a lot of time into SWTOR online, but started to replay Neverwinter Nights: Diamond Edition. I can blame GOG and their specials for getting me back into Neverwinter. Also started playing TOS: Arena. I had to laugh at the giant pixel graphics and tinny midi-music, they were so dramatic.