I typically beat most games I sit down to play. Notable exceptions are RE5 and Halflife 2.
ME... oh man...
I have played that game perhaps too much... as there's been a lot of ME2 threads around, I've disclosed this several times.. but I have played through the game doing all of the side missions, approximately 6 times... I'm working on the 6th that I can recall... I also beat it without doing the missions on Insanity mode for the achievement (screw doing all that work on Insanity, that's insane).
I actually really love the exploration in Mass Effect.. the story is only one of the things that is pretty good.. what's better is the setting.. the characters, the aliens, the locations.. I love them all.