I've put in a lot of time and effort with both, and enjoyed them, but I don't think I'm ever going to see them through to the end.
I finally beat Death in Rondo of Blood last time I played, woot! The next level is a boss gauntlet... Oh well, as a kid I never beat Castlevania or Castlevania III, both of which I really loved, so why should Rondo be any different? These old school Castlevanias are just hard as hell. The more forgiving playability (you might say easiness) of Symphony of the Night is a big part of why it's lodged solidly in my top three games of all time.
As for San Andreas, well, I've really just had enough GTA altogether. I was pretty much done after Vice City, and even though I'm sitting at around 75% of the way through the story of San Andreas, I haven't been playing it or having fun with it the way I did with the first two entries in this incarnation of the series. The days of GTA III and Vice City were the halcyon days of collegiate life in the dorm. My roommate and I would trade the controller back and forth over these two games and just have a blast for hours at a time. When I play San Andreas now, I'm solo, and it's just not that involving. I'd rather just cut to the chase, and to play a GTA game that way just isn't right, so I'm going to just walk away.
Lord knows I've got other stuff I could be playing.
I am getting GTA IV, but if I hadn't already had it on order for the awesome bargain price of $42 since a year or more ago, I might have held off for a while. I just hope the jump up to "IV" brings some significant differences to the formula. The story and presentation looks pretty good this time around, at least.