The Hotdog Laserhouse

Well, I don’t know that Twilight Princess had a ton of fetch quests, either. It was more that…

1. The game sets up your next destination as THE SKY TEMPLE
2. BUT FIRST: You have to restore Ilia’s memory. Take a note from Renaldo to Telma’s bar.
3. Show Telma the note, and she tells you to see the doctor across town.
4. Talk to the doctor and he’ll point you towards one of Ilia’s keepsakes that was stolen.
5. You track the keepsake back to the bar where Telma’s cat Louise tells you it was taken by some monsters.
6. Defeat the monsters, get the keepsake, go back to Kakariko village and give it to Ilia. She remembers a hidden village and the person who originally rescued her.
7. Remember: It was established our main goal was to get to the Sky Temple. The Hidden Village is not the sky temple.
8. Go to the hidden village and rescue an old lady that saved Ilia. She will give you a completely separate keepsake, which you then take back to Ilia again.
9. Ilia’s memory is finally fully restored and you find out the keepsake is a horse whistle that is completely worthless at this point in the game because you can just teleport everywhere.
10. Now that Ilia remembers everything, you are told to go back to the Hidden Village and show the old lady an item because she knows what it is.
11. The old lady gives you a book, which you must them return to give to a character in Kakariko Village. 
12. The book is missing an important word, and six locations are marked on your map that you have to travel to in order to fill in the blanks.
13. 30 minutes to an hour later you finally have a complete book, and you return to Kakariko Village to show the guy who wants the book. You figure out the secret and discover an old, decrepit cannon.
14. You take the cannon to a dude who repairs cannons, and he says he’ll fix it for 300 rupees. At this point, I was literally out of rupees, because I’d spent them all on the MaloMart Magic Armor. So I have to spend another hour scouring Hyrule Field for chests of rupees I haven’t already opened.
15. He repairs the cannon, and finally, 2-4 hours after being told I need to go to the Sky Temple, I finally have access to it.

The entire game is like that. What normally appears to be a straight-forward objective ends up having a 15 step process before you get to it, and it is almost always tedious.

As for other overly-long games I’ve played, it depends on what you mean. If we’re talking games I played for a long time…

Final Fantasy VII - I gave this game more than 100 hours of my life. I did literally everything possible, and I did it all without a guide. Mastered every Materia, got the majority of the characters in the game to level 99, unlocked all of their Limit Breaks, bred and raced a Gold Chocobo, acquired Yuffie and Vincent AND did their optional quests… you get the picture. I also, of my own volition, developed and discovered a way to trap my party in an attack loop that could be used to basically kill anything in the game. Never done that with any other RPG since.

Grand Theft Auto: San Andreas - I have developed a problem in games called “What’s Over There”-itus, and GTA:SA really fed in to that in a big way because the world is absolutely huge. Every time I unlocked a new island, I would spend hours just driving around every single road and exploring the vast open spaces. And then I lost my save file, so I ended up doing it all twice. According to Xfire, I have spent 148 hours in GTA:SA.

GTA4 - It makes sense that if two full-playthroughs of GTA:SA took 150 hours, that one single playthrough of GTA4 would be at about 70 hours. And that’s exactly right.

Phantasy Star Online - Not the longest game in the world, but as with any good multiplayer game, you end up playing it a lot. I put probably 200 hours in to this?

Left4Dead 2 - And finally, the coup de grace. As mentioned with PSO above, multiplayer games can last you a while even without a ton of content, and according to Xfire, I have put in 535 hours in to Left4Dead 2 with my friends, making it my most played game of all time by a significant margin.

As for Sly Cooper, I’ve never played one of those games, actually! And I even own the first one on PS2. I just haven’t gotten around to playing it yet. They always looked cool, but later games sounded like they were starting to suffer from Sonic Syndrome with the number of playable characters that were not Sly Cooper himself.