Pacing (or Prolonging the Magic)

I suffer from the self-defeating mentality of "I love this game.  Im gonna play it until I hate it."

While that is a little extreme, it isnt far from the truth in my case.  I look for a game that I enjoy and then I play the crap out of it.  One day, BAM, I dont want to play it anymore.  There are games in my collection that I insist on holding onto, because they were once the game.  The game that kept me up at night and distracted me from work.  Now, I look at them on my shelf and I cant bring myself to play them.  I need something new and something great.  What causes this?  Is it because I saturate myself with a game?  Is it the constant inundation of previews of the next great unreleased game that overshadows my now seemingly outdated favorite?

Right now I am split between two games, as Ive mentioned earlier.  I get my online jollies from BF2 and I get a ton of immersion in Oblivion.  Online games are their own animal. As long as I have a friend that occasionally plays the game Ill keep it and play when we can. 

Last night I was playing Oblivion, and I found myself torn.  How do I want to play this amazing game?  Do I finish the main quest?  Ive done the Arena and the DB guild line.  Im almost done with the Mage line, and I could easily continue where I left off on the Fighters line.  The question is what to do first.  Something about this game has me hooked and I dont want to lose it.  Im in this environment where I can do whatever I want, but there is a larger story looming in the background.  I want to finish the main story and get the dragon armor and experience the epic storyline.  Will I still want to do all of the other stuff after I do that?  Should I at least close every Oblivion gate before I do it? 

The obvious answer is that I should go about the game the way I will most enjoy it.  The funny thing is that I dont know how.  I am the guy that separates teh purple and red skittles from the rest.  Ill eat the other by the handful and then go back and enjoy my two favorites one at a time.  Here, I cant figure out which would be more fun.  Which way would allow me to play this game longer and not get bored with it?