What part of a game you enjoy replaying do you dislike replaying?
I love the original Hotline Miami but I'm not a big fan of the boss fights like the ones in Neighbors (Biker) and Deadline (Van Driver). I find it kind of slows down the game and limits the strategies you can take.
Another example would be Fallout 3. I find the tutorial section in Vault 101 can feel a bit long after a fifth run but maybe that's because I was spoiled by Fallout New Vegas' ability to run off in your own direction immediately after leaving Doc Mitchell's house.
The main thing that keeps me from reinstalling and trying to play Skyrim again is the thought of having to do Bleak Falls Barrow for the billionth time. Yeah, I could mod around it, but I just don't care enough to figure out how for a game I pretty much always play through the first few hours of and then drop for another three years anyways.