Never wanted to end:
Roller Coaster Tycoon
Portal 2
Paper Mario: The Thousand-Year Door
Walking Dead: Seasons 1 AND 2

Games I wanted to end:
Zelda: Skyward Sword
Super Mario Galaxy (Getting 121 was awesome, doing the exact thing over again for 100% wasn't as fun)
Smash Bros Brawl (The last bit of the Subspace Emissary was overwhelming)